Upgrade-requirements

- Enhancement: ([5](https://github.com/joeyespo/grip/pull/5) - thanks, [ldsink][]!)
- Enhancement: Handle "No requirements to upgrade" edge case

- Enhancement: Handle spaces around requirements package names ([4](https://github.com/joeyespo/grip/pull/4) - thanks, [ldsink][]!)

- Enhancement: Handle comments in requirements file ([2](https://github.com/joeyespo/grip/pull/2) - thanks, [emilecaron][]!)

- Enhancement: Python 3 support
- Bugfix: Fix potential Unicode errors in `pip show` output

- Initial commit of working project


[emilecaron]: https://github.com/emilecaron
[ldsink]: https://github.com/ldsink