Upgrade gradle to match the version in react native.

Change url of react native repository so that it loads the correct local version.

android/build.gradle

@@ -4,7 +4,7 @@ buildscript {
     }
 
     dependencies {
-        classpath 'com.android.tools.build:gradle:1.1.3'
+        classpath 'com.android.tools.build:gradle:2.1.0'
     }
 }
 
@@ -30,7 +30,7 @@ repositories {
     jcenter()
     maven {
         // All of React Native (JS, Obj-C sources, Android binaries) is installed from npm
-        url "$projectDir/../../node_modules/react-native/android"
+        url "$projectDir/../../../node_modules/react-native/android"
     }
 }