Force ant and android studio to use Java7

build.gradle

@@ -53,10 +53,13 @@ android {
         release.setRoot('build-types/release')
     }
 
-    android {
-        lintOptions {
-            abortOnError false
-        }
+    compileOptions {
+        sourceCompatibility JavaVersion.VERSION_1_7
+        targetCompatibility JavaVersion.VERSION_1_7
+    }
+
+    lintOptions {
+        abortOnError false
     }
 
     productFlavors {

project.properties

@@ -11,3 +11,5 @@
 target=android-22
 android.library.reference.1=owncloud-android-library
 android.library.reference.2=libs/android-support-appcompat-v7-exploded-aar
+java.source=7
+java.target=7