[FEATURE] Use --classmap-authoritative for composer install

This creates an optimized class map and denies lookups
for classes not in the class map, which speeds up class_exist
checks by a lot.

Downside is only a slightly higher build time.

Tests/Unit/Task/Composer/InstallTaskTest.php

@@ -33,7 +33,7 @@ public function executeUserConfiguredComposerCommand()
         );
 
         $this->task->execute($this->node, $this->application, $this->deployment, $options);
-        $this->assertCommandExecuted('/^\/my\/path\/to\/composer.phar install --no-ansi --no-interaction --no-dev --no-progress 2>&1$/');
+        $this->assertCommandExecuted('/^\/my\/path\/to\/composer.phar install --no-ansi --no-interaction --no-dev --no-progress --classmap-authoritative 2>&1$/');
     }
 
     /**

src/Task/Composer/InstallTask.php

@@ -74,7 +74,7 @@ protected function buildComposerInstallCommands($manifestPath, array $options)
         }
         return array(
             'cd ' . escapeshellarg($manifestPath),
-            escapeshellcmd($options['composerCommandPath']) . ' install --no-ansi --no-interaction --no-dev --no-progress 2>&1',
+            escapeshellcmd($options['composerCommandPath']) . ' install --no-ansi --no-interaction --no-dev --no-progress --classmap-authoritative 2>&1',
         );
     }