Add support for Travis CI

Travis CI is a free continuous integration service. Right now, since our
unit tests are broken, this only tests that the code compiles. This lets
us avoid breaking the build when accepting pull requests.

Whenever someone opens a pull request, Travis should show if it breaks
the build inline with the issue tracker.

I also turned compiler warnings into errors, so Travis will break on
those, which means that we need to fix the compiler warning introduced
by issue #13 before this is useful.
Enable IRC notifications for Travis CI
Merge branch 'fix-warnings' into travisci
Merge pull request #14 from ipop-project/travisci

Add support for Travis CI