Offlinedatasci

* Move install all functionality into Python interface (93 by ethanwhite)
* Switch from urllib.request.urlopen to requests to handle gzipped web pages (111 by ethanwhite)
* Don't try to create PyPI mirrors for non-Windows OSs on Windows (115 by abhidg and ethanwhite)
* Ensure that PyPI mirror matches version of Python (116 by ethanwhite)

* Allow installing R packages that match the current version of R (instead of the system version)
* Updates to the readthedocs system

* Improve testing
* Add docs

- Improvements to handling external R dependency (57 by ethanwhite)
- Add installation instructions (58 by abhidg)
- Remove unused dependencies (57 by ethanwhite, 59 by abhidg)
- Fix R downloads (64 by ethanwhite, 74255ae by garezana)
- Better exception handling (67 by garezana)
- Start a test suite (68 & 69 by ethanwhite and garezana)
- Add Library Carpentry lessons (71 by ethanwhite)
- Fix miniCRAN installation (70 by ethanwhite)

Initial release on PyPI