change buildtools for travis

Author: Tneciv

.travis.yml

@@ -7,7 +7,7 @@ android:
     - tools
 
     # The BuildTools version used by your project
-    - build-tools-23.0.1
+    - build-tools-23.0.2
 
     # The SDK version used to compile your project
     - android-23

app/build.gradle

@@ -2,7 +2,7 @@ apply plugin: 'com.android.application'
 
 android {
     compileSdkVersion 23
-    buildToolsVersion "23.0.1"
+    buildToolsVersion '23.0.2'
     defaultConfig {
         applicationId "com.tneciv.zhihudaily"
         minSdkVersion 16