Use travis' beta OS-X build support.

http://blog.travis-ci.com/2014-05-13-multi-os-feature-available/
Merge pull request #5 from pipelang/phs/travis-osx

Use travis' beta OS-X build support.
apt-get install coq.

This annoyingly brings in all of gtk2 through a required ocaml
transitive dependency.
Extract `doc/virtualization.md`.
Start a latex book, where we will keep the coq proofs.
Begin the meta theory chapter.