Upgraded Gradle to 2.2.1 and Android Gradle Plugin to 1.0.0

Change Log:
Upgraded Android Gradle Plugin from  0.12.2 to 1.0.0
Upgraded to Gradle to 2.2.1 as Android Gradle Plugin 1.0.0 requires 2.2.1
Replaced 'com.android.support:support-v4:[20,21)' with com.android.support:support-v4:21.0.3

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Notes:
Gradle is 2.2.1 is the latest Gradle Release
Android Gradle Plugin 1.0.0 is latest and officialy launched along with Android Studio 1.0(Stable Release)
Android Studio is now Official Android IDE and Eclipse Plugin will no longer be officialy supported after complete migration of NDK and other few other featues to Android Studio.
http://developer.android.com/sdk/index.html
http://developer.android.com/tools/revisions/studio.html
http://developer.android.com/tools/sdk/eclipse-adt.html