Travis CI

[langston-barrett]

Would you all be interested in a pull request providing a .travis.yml similar to (probably the same as) my PR at math-classes?

[spitters]

Yes, that would be great.

[langston-barrett]

@spitters I'm having some trouble building in Travis. Is there some step I should take to download math-classes before building corn? Should I opam install it?

Might be good for the README as well :)

[spitters]

Yes, opam is probably the way to go. We went back and forth a bit. We used to use git submodules, but they don't interact very well with opam, which is what the coq-devs want. So, the last changes I made where to use opam.