Autopep8

Used [autopep8](https://github.com/hhatto/autopep8) to make all of pandas py files more PEP8 compliant (Excluding 230 `E501 lines too long` (over 80 chars), and 6 changes which had to be reverted to fix test failures - in second commit). See statistics in my comment.

I iterated over every py file in the package using [autopep8](https://github.com/hhatto/autopep8), inspected the output of [pep8](https://github.com/jcrocholl/pep8) to drill-down and consider any compliance issues found which may change the meaning of the code (and considered those individually).

I haven't included a unittest for PEP compliance using pep8.

For me this passes all the same tests as the master branch.

*Since this affects such a large set of the code it may not be reasonable to pull, however it is certainly a proof of concept.*