CB-5982:  Android Platform guide improvements

I have clarified some steps(same for Amazon FireOS), 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:

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