script -> library

Hey Sam!

The main change here is removing the interface from the `videogrep.py` file and moving it to a `videogrep_cli.py` file. Upon installation using `python setup.py install` the cli file will be placed into the /usr/bin/. This file will pull the functionality from the videogrep library installed in the user's site-packages. 

The main benefit of this is that users can now `from videogrep import videogrep` and construct commands. 

I also added a couple tests, but they do not prove much and frankly need work.

How does this look to you? Have I maintained the spirit of the project?

Thanks,
Dean