Added console executable godaddy, config support via ~/.godaddyrc

Hi, thanks for your pygodaddy library, I find it very useful.

I am submitting this pull request to extend shell support in two ways:

1. `godaddy` provided as a command line executable
2. login via CLI args, `~/.godaddyrc`, or any other file path

I find it worthwhile to bump the version to 0.2.0 as this is not an iterative bug fix release.

Notes:
- license header comment blocks - let me know what you prefer, I can copy/paste license blocks from other files as a follow-up commit
- your previous unit tests can be ported to use the new config convention, but I think that should be done in a separate branch.
- at your comfort level: if you'd like to add me as a PyPi maintainer, my username is `Anthony.Wu`

– Anthony