Upgraded gradle wrapper and build tools

build.gradle

@@ -3,7 +3,7 @@ buildscript {
         mavenCentral()
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:0.12.1'
+        classpath 'com.android.tools.build:gradle:0.13.3'
         classpath files('gradle/libs/gradle-witness.jar')
     }
 }

gradle/wrapper/gradle-wrapper.properties

@@ -2,4 +2,4 @@ distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=http\://services.gradle.org/distributions/gradle-1.12-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-2.1-all.zip