Update all app project files

gradle/wrapper/gradle-wrapper.properties

@@ -1,6 +1,5 @@
-#Wed Aug 12 13:33:05 NZST 2015
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-2.6-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-2.13-all.zip