setup Travis CI for testing

* [x] It's still necessary to [activate a webhook](http://docs.travis-ci.com/user/getting-started/) to test pull requests 
Right, well - they both should do the same, but I forgot that's not actually true - I use -gocheck.v when running tests in a given subdir and it gives nicer output - it does choke when no *_test.go files exist in the root dir though.

Fair enough - no need to go get gocheck then.