Update handler docblocks

system/Cache/Handlers/DummyHandler.php

@@ -65,7 +65,7 @@ public function remember(string $key, int $ttl, Closure $callback)
 	 * @param mixed   $value The data to save
 	 * @param integer $ttl   Time To Live, in seconds (default 60)
 	 *
-	 * @return mixed
+	 * @return boolean Success or failure
 	 */
 	public function save(string $key, $value, int $ttl = 60)
 	{
@@ -79,7 +79,7 @@ public function save(string $key, $value, int $ttl = 60)
 	 *
 	 * @param string $key Cache item name
 	 *
-	 * @return boolean
+	 * @return boolean Success or failure
 	 */
 	public function delete(string $key)
 	{
@@ -135,7 +135,7 @@ public function decrement(string $key, int $offset = 1)
 	/**
 	 * Will delete all items in the entire cache.
 	 *
-	 * @return boolean
+	 * @return boolean Success or failure
 	 */
 	public function clean()
 	{

system/Cache/Handlers/FileHandler.php

@@ -111,7 +111,7 @@ public function get(string $key)
 	 * @param mixed   $value The data to save
 	 * @param integer $ttl   Time To Live, in seconds (default 60)
 	 *
-	 * @return mixed
+	 * @return boolean Success or failure
 	 */
 	public function save(string $key, $value, int $ttl = 60)
 	{
@@ -149,7 +149,7 @@ public function save(string $key, $value, int $ttl = 60)
 	 *
 	 * @param string $key Cache item name
 	 *
-	 * @return boolean
+	 * @return boolean Success or failure
 	 */
 	public function delete(string $key)
 	{
@@ -253,7 +253,7 @@ public function decrement(string $key, int $offset = 1)
 	/**
 	 * Will delete all items in the entire cache.
 	 *
-	 * @return boolean
+	 * @return boolean Success or failure
 	 */
 	public function clean()
 	{

system/Cache/Handlers/MemcachedHandler.php

@@ -202,7 +202,7 @@ public function get(string $key)
 	 * @param mixed   $value The data to save
 	 * @param integer $ttl   Time To Live, in seconds (default 60)
 	 *
-	 * @return mixed
+	 * @return boolean Success or failure
 	 */
 	public function save(string $key, $value, int $ttl = 60)
 	{
@@ -238,7 +238,7 @@ public function save(string $key, $value, int $ttl = 60)
 	 *
 	 * @param string $key Cache item name
 	 *
-	 * @return boolean
+	 * @return boolean Success or failure
 	 */
 	public function delete(string $key)
 	{
@@ -313,7 +313,7 @@ public function decrement(string $key, int $offset = 1)
 	/**
 	 * Will delete all items in the entire cache.
 	 *
-	 * @return boolean
+	 * @return boolean Success or failure
 	 */
 	public function clean()
 	{

system/Cache/Handlers/PredisHandler.php

@@ -138,7 +138,7 @@ public function get(string $key)
 	 * @param mixed   $value The data to save
 	 * @param integer $ttl   Time To Live, in seconds (default 60)
 	 *
-	 * @return mixed
+	 * @return boolean Success or failure
 	 */
 	public function save(string $key, $value, int $ttl = 60)
 	{
@@ -176,7 +176,7 @@ public function save(string $key, $value, int $ttl = 60)
 	 *
 	 * @param string $key Cache item name
 	 *
-	 * @return boolean
+	 * @return boolean Success or failure
 	 */
 	public function delete(string $key)
 	{
@@ -242,7 +242,7 @@ public function decrement(string $key, int $offset = 1)
 	/**
 	 * Will delete all items in the entire cache.
 	 *
-	 * @return boolean
+	 * @return boolean Success or failure
 	 */
 	public function clean()
 	{

system/Cache/Handlers/RedisHandler.php

@@ -169,7 +169,7 @@ public function get(string $key)
 	 * @param mixed   $value The data to save
 	 * @param integer $ttl   Time To Live, in seconds (default 60)
 	 *
-	 * @return mixed
+	 * @return boolean Success or failure
 	 */
 	public function save(string $key, $value, int $ttl = 60)
 	{
@@ -212,7 +212,7 @@ public function save(string $key, $value, int $ttl = 60)
 	 *
 	 * @param string $key Cache item name
 	 *
-	 * @return boolean
+	 * @return boolean Success or failure
 	 */
 	public function delete(string $key)
 	{
@@ -288,7 +288,7 @@ public function decrement(string $key, int $offset = 1)
 	/**
 	 * Will delete all items in the entire cache.
 	 *
-	 * @return boolean
+	 * @return boolean Success or failure
 	 */
 	public function clean()
 	{

system/Cache/Handlers/WincacheHandler.php

@@ -83,7 +83,7 @@ public function get(string $key)
 	 * @param mixed   $value The data to save
 	 * @param integer $ttl   Time To Live, in seconds (default 60)
 	 *
-	 * @return mixed
+	 * @return boolean Success or failure
 	 *
 	 * @codeCoverageIgnore
 	 */
@@ -101,7 +101,7 @@ public function save(string $key, $value, int $ttl = 60)
 	 *
 	 * @param string $key Cache item name
 	 *
-	 * @return boolean
+	 * @return boolean Success or failure
 	 *
 	 * @codeCoverageIgnore
 	 */
@@ -177,7 +177,7 @@ public function decrement(string $key, int $offset = 1)
 	/**
 	 * Will delete all items in the entire cache.
 	 *
-	 * @return boolean
+	 * @return boolean Success or failure
 	 *
 	 * @codeCoverageIgnore
 	 */