Update the registerWidget documentation

Closes #241
Test configs don't inerit from confreader.File

Not sure why I originally did this, but it's unneeded (and in fact causes
problems; user configs are read during testing, which is obviously a no-no).
Mention setuptools in docs, s/xpyb-ng/xpyb
Remove unused docs

Also add releases to table of contents so as not to generate an unused
warning.

I didn't configuration.rst because it looks like that still needs some porting work.
Modified widget/base.py to line up windowname

There was apparently a rounding error in the calculation.
generalized symbols for yahoo weather

Closes #259
Merge branch 'defaults-refactoring' into develop

Conflicts:
	libqtile/widget/yahoo_weather.py

Closes #258
Added GoogleCalendar widget

@tych0: Minor formatting changes, removed commented out code.
Add line accidentally deleted from google calendar

Closes #262