bump version to 0.2.2
Start work on RTFD.org docs.
Document expect class.
Fix formatting.
Finish the basic docs.

I wasn't sure of a couple things so I took a stab in the dark. @garybernhardt
will have to confirm/edit the documentation.
Merge remote-tracking branch 'sigmavirus24/docs'
update docs
rename CustomExpectation -> _CustomExpectation
clean up doctests
run doctests with tests
add test for docs
split tests into unit and docs
add doc link to readme
Allow isinstance to take multiple classes.

e.g.

expect('str').isinstance((str, bytes))
Add a test for isinstance((cls1, cls2, cls3, ...))
remove long reference (breaks in Python 3)
rename test