ANE Google Analytics v2.0.7 RC1

This is a release candidate for the next release as it's still under testing and the final version may be contain different API and/or features.
This prerelease focuses on Android devices but I'll try to offer the same functionalities on iOS as well before the final release.

• Upgraded to AIR 13
• Upgrade Android native library to v2.0beta6
• Added ASDocs back into packaged release
• Implemented Google Play Campaign Attribution tracking (Android only)
• Implemented General Campaign & Traffic Source Attribution (Android only)
• Added transaction's currency code property (Android only)
• [Android] Verify app has needed permissions when checking if extension is supported
• Fixed issue #32 - transaction's shipping cost being replaced by tax cost
• Fixed issue #34 - improved app version identification from descriptor