[TIMODOPEN-212] Admob: Android-updating SDK to 6.2.1 and building with 2.1.3.GA

Updating documentation
Making guid match iOS version
[TIMODOPEN-212] Admob: iOS-updating SDK to 6.2.1 and building with 2.1.3.GA

Updating documentation
Merge pull request #51 from jonalter/TIMODOPEN-212

[TIMODOPEN-212] Admob: updating SDK to 6.2.1