Fix gradle and supresswarnings issue

build.gradle

@@ -24,7 +24,7 @@ apply plugin: 'pmd'
 apply plugin: 'findbugs'
 
 ext {
-    supportLibraryVersion = '25.2.0'
+    supportLibraryVersion = '24.0.0'
 
     travisBuild = System.getenv("TRAVIS") == "true"
 
@@ -193,7 +193,7 @@ dependencies {
     androidTestCompile 'com.android.support.test:runner:0.5'
 
     // Android Annotation Support
-    androidTestCompile "com.android.support:support-annotations:${supportLibraryVersion}"
+    androidTestCompile "com.android.support:support-annotations:25.0.0"
 
     // Espresso core
     androidTestCompile 'com.android.support.test.espresso:espresso-core:2.2.2'

src/main/java/com/owncloud/android/MainApp.java

@@ -52,6 +52,8 @@ import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 
+import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
+
 
 /**
  * Main Application of the project