Add support for offline rendering via misaka.

Right now doesn't support gfm user content, github styles.
Cache retrieved styles to be used offline.
Use Python-Markdown instead of misaka.
Merge pull request #11 from isbadawi/offline-rendering

Offline rendering
Upgrade requests to 1.2.3.
Rename initial_args to standard argv.
Add note about relative URLs, using AUTHORS.md.
Remind authors to add themselves to AUTHORS.md.
Link Authors.md back to Readme.
Remove Patches and Suggestions title.
Update contributors.
Remove package_data from setup.
Merge branch 'master' of github.com:joeyespo/grip

Conflicts:
	README.md
Add attribution in CHANGES.md.