Clean up left over egg-info directory
Supporting methods for the encrypt() method

* Added the ability to get GPG configuration parameters from the GPG binary in use
* Added the ability to see lists of available compression, digest and encryption types you can use with the encrypt() method
* Wrote out encrypt()'s docstring so I'd know how I want it to work
Install GnuPG 2 on the Travis CI instances
New error class
Working encrypt()!

This works now and there are tests for the encryption functions, as much as you can test encryption in a test framework without exposing your private key associated with your Keybase user ID, in the test/ directory.

Documents are up-to-date as well.
Merge branch 'feature/encrypt' into develop