Pip-tree

- Fixed reference of `PIPPIN_PIP` to `PIP_PATH` now that the package has been renamed
- Removed unused pip variables in favor of the constant `PIP_PATH`
- Updated documentation

- Refactored Pippin from a shell script to a Python script
- Now retrieve the pip list as JSON
- Now retrieve the pip package details as RFC-compliant mail header format
- Now with Python, we shell out to pip and run the commands but retrieve the data as machine parseable instead of human readable and chopping it up after the fact
- Added unit tests, updated docs, added Makefile
- Changed name from `Pippin` to `Pip Tree`... stupid PyPi naming rules

- Added the version number of the packages to the output
- Removed redundant file deletion to boost performance and decrease file manipulation calls
- Added documentation to better explain what each function does
- Small tweaks throughout

- Initial release
- Pippin will generate a report of the dependency breakdown of your Python virtual environment
- Pippin will say the number of dependencies in an environment
- Pippin will take an optional argument allowing you to specify which virtual environment (path to pip) to use