Update project to Leiningen 2

* Update .gitignore to Lein 2 structure
* Add profiles for different Clojure versions
Update Apache POI version to 3.9
Add alias for 'all' for all profiles
Add .travis.yml to support running tests using Travis CI
Merge pull request #12 from ragnard/updates

Updating project and dependencies (Lein 2, Clojure 1.3-1.5 RC, POI 3.9)