Refactors _file_processor class to a function

[ajm188]

Resolves #53

I also took advantage of the opportunity to clean up some of the pep8 complains in tests/cmd/main_test.py.

Two things:

1. We now have undebt.cmd.main.process and undebt.cmd.logic.process. We may want to merge these two methods.
2. I'm not sure how valuable all of these tests in tests/cmd/main_test.py are now, since a few of them were verifying behavior of _file_processor objects.

[paiweilai]

1. I am fine with the merging.
2. this is 2? :p

[evhub]

LGTM, although GitHub is indicating there are conflicts, so you should probably rebase first.

[ajm188]

hehe yeah isn't markdown nifty?

I need to rebase, since I bumped the version in the PR I just merged. I'll let travis run before I merge it.

This is going to be a patch release.

[ajm188]

Rebase then version bump

[ajm188]

Bump :)

[paiweilai]

sheep!