Highlight Android and mobile on home page
Merge pull request #93 from townxelliot/android-mobile-1306

Highlight Android and mobile on home page
Clean up sample text and links
Add SIMD sample description
Update links for new crosswalk-samples version
Update unwieldy paragraph
Add SIMD sample icon
Add note about minimum version of Crosswalk + arch required for SIMD

Only works on beta Crosswalk on x86.