Fix links on github homepage.

Links to Build Instructions and Programmer's Guide were broken.

Bug: 17383489
Tested: Testing is difficult. The links are absolute paths, so they
should work.

Change-Id: I5a95770d667fe65cfb1e23f3000d0d360856d88d
Merge freeglut
Merge googletest
Merge liquidfun
Copy Readme.md to the project root.

Tested: Hard to test, but the existing Readme.md (in 'liquidfun'
directory has links that work.
Fix logo link in Readme.md.