extracted gradle dependency versions into the root build.gradle file (one place for all sub modules)

build.gradle

@@ -22,3 +22,23 @@ allprojects {
 	    targetCompatibility = "1.7"
     }
 }
+
+// dependency versions for all sub modules
+ext {
+    // regular
+    buildTools = "22.0.1"
+    compileSdk = 22
+    minSdk = 14
+    targetSdk = 22
+
+    support = "22.1.1"
+    play_services = "7.3.0"
+
+    // testing - jvm
+    junit = "4.12"
+    mockito = "1.9.5"
+
+    // testing - ui
+    test = "0.2"
+    espresso = "2.1"
+}