Libraries should not include Gemfile.lock

Libraries should be more liberal with their dependencies than
applications to allow bundler to select dependencies with the best
chance of avoiding conflicts
Initial support for Travis-CI
Combine memory and filesystem tests under Travis-CI

* Update Rakefile with new Travis-CI task
* Fix FileSystem tests (had same name as memory ones)
* Update travis config file to call new task
Add MongoDB tests to the Travis-CI tests
Add the "mongo" development dependency

We do not want to include storage specific dependencies in production
however for a developer hacking on Ankusa it is a different matter.
Add the "mongo" development gem dependency to the gemspec to avoid
people (and Travis-CI) having to do it themselves
Merge pull request #4 from rurounijones/travis-ci-support

Improved Travis ci support