Broken after "32-bit/64-bit Makefile fix" commit.
Ubuntu "Precise" 12.04.5 supports multilib only until
g++ 4.6 that is not enough to compile Stockfish.
So move to Ubuntu 14.04.4 LTS (Trusty Tahr)
No functional change.
Add Travis CI support to GitHub repo.
After every push to master, Travis will build
the sources directly from GitHub repo according
to .travis.yml and verify everything is ok.
No functional change.