Brought in the mapping class from ee6e5fd4a

- Thanks, @aquamatt!
Mapping type!

Also did a million other things, so here's hoping we don't need to
roll back:
- Lint lint lint...still not sure about long URLs busting past 100
  cols in core.py, need to look into ReST tricks for that
- Broke tests into their own path, split them out by module
- Added requirements files, mainly for test requirements
  dev requirements file is only helpful if you don't already
  `pip install -e .` dev projects with working setup.py files
- unittest2 is now in tests_require where it belongs
Version bump to 0.3.0a1, we'll see what travis has to say about this...
Updated documentation examples for attributes and Metadata

This provides fixes to documentation for various metadata usage examples
as well as detailed examples of usage for Resource attributes.
Normalize quotes

- Single quote for strings, double quotes for docstrings
Super-prviate method now merely private

- I don't see that this method needs name mangling to succeed,
  am I missing something?
Developer docs, minor tweaks
Merge remote-tracking branch 'upstream/pr/19' into develop
No more sphinx warnings!
Using semantic_version instead of verlib
Minor lint fix
Merge branch 'master' into develop