Android Platform guide, updates & improvements

JIRA issue: https://issues.apache.org/jira/browse/CB-5982

I have clarified some steps, and improved the AVD Emulator guidance in the Android Platform.

Some more information about how to work with Intel Atom x86 System Images as well detailed information about how to use Virtualization Technologies with the AVD Emulator.

References about the information provided:

https://downloadcenter.intel.com/Detail_Desc.aspx?ProductID=1881&DwnldID=7838
https://downloadcenter.intel.com/Detail_Desc.aspx?ProductID=1881&DwnldID=7840&lang=eng
http://software.intel.com/en-us/android/articles/speeding-up-the-android-emulator-on-intel-architecture
http://ark.intel.com/products/virtualizationtechnology
http://en.wikipedia.org/wiki/X86_virtualization
http://support.amd.com/TechDocs/50911_15h_Mod_10h-1Fh_A-Series_PDS.pdf#search=AMD%2DV%20support
http://developer.amd.com/wordpress/media/2012/10/33610_0Fh_Rev_Gd.pdf
http://support.amd.com/en-us/kb-articles/Pages/emb-309-npt.aspx
http://news.cnet.com/8301-13924_3-10235329-64.html
http://developer.android.com/tools/help/emulator.html
http://developer.android.com/tools/devices/emulator.html