set java version to 1.7
diff --git a/gradle.properties b/gradle.properties
index a081b22..a857309 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -6,5 +6,5 @@
  * http://www.eclipse.org/legal/epl-v10.html
  */
 
-sourceCompatibility=1.8
-targetCompatibility=1.8
\ No newline at end of file
+sourceCompatibility=1.7
+targetCompatibility=1.7
\ No newline at end of file