Feat/tests

#### Problem

At the moment when you want to test the gem, you need to include it in a separate project. Relates to https://github.com/revett/rake-rspec/issues/3.

#### Solution

Have a sample application (in this case a single class) which can be tested with **Rake::RSpec** and the spec directory structure it suggests.

For reference:

`rake spec` tests `Batman.who_am_i?`
`rake integration` tests `Batman.harvet_dent`
`rake all` tests both class methods.