Change to 1.8

Signed-off-by: Mario Danic <mario@lovelyhq.com>

build.gradle

@@ -112,8 +112,8 @@ android {
     }
 
     compileOptions {
-        sourceCompatibility JavaVersion.VERSION_1_7
-        targetCompatibility JavaVersion.VERSION_1_7
+        sourceCompatibility JavaVersion.VERSION_1_8
+        targetCompatibility JavaVersion.VERSION_1_8
     }
 
     packagingOptions {