New command structure for bin/hotcocoa

[isaac]

This issue was born from a discussion on this pull request: https://github.com/ferrous26/hotcocoa/pull/18

Here is the relevant quote from Mark:

I have been thinking about a command structure for bin/hotcocoa, as it means there can be less logic in that file specifically and hopefully that makes it easier to test (and extend)

[ferrous26]

Ok, something will definitely happen with this for 0.7. There will have to be a command class or a command namespace for the growing number of commands.

The only question now is if it should be exposed through rake or through the hotcocoa binary.