Add cljsbuild hooks

This allows us to run commands without the cljsbuild prefix:

```
$ lein compile
$ lein clean
$ lein test
```
Add default build and test command for 'lein test'

This allows us to build and run the tests (once) with 'lein test'. This
is useful for travis-ci.
Add travis-ci configuration
Add travis-ci badge to README
Update compile instructions in README
Merge pull request #12 from clojure-rica/travis-ci

Add Travis CI