Add easy style sheet selection.
Add rc_params_in_file to return partially-filled RcParams

This allows style sheets to update the current settings instead of overwriting them.
Rename style files to `*.style`
Allow style.use to open URLs
Remove pyplot import
Add style context manager and tests
Change style extension to *.mplstyle
Got a little crazy with the whitespace
Add style package and data to setupext.py
Move test so that it actually runs.
Use explicit string check
Hide rc_params_in_file from parent namespace
Remove usage of import *
Clarify docstring
added `matplotlib.style` to pyplot import list
fix url rc specification

smoothed over conflicts

add test for URL stylesheet

whoops, remove extraneous regex I added...

move test to proper location

arg, don't need urllib2 either...didn't realize functionality was in core mpl
fixed divergent naming scheme
pep8 clean up
Add docs for style package
Import style package for easy use.