Add basic Travis CI configuration

I added a basic Travis CI configuration to make the build status more
transparent. I added a small logo to the bottom of the README with the
status and a link to the build.

@evancz after merging this you'd have to go to https://travis-ci.org
and enable the build for this project, just takes a couple of clicks.
See http://about.travis-ci.org/docs/user/getting-started/.

I tested this on my own github account and the configuration worked
(ie, it showed the same build errors on Travis that I'm experiencing
locally).
resolve conflict in README!
Merge branch 'jsl-add_travis' into dev