Fixed PEP 8 coding style violations (all but E501)

`pep8 --ignore=E501 --exclude=conf.py,tomopy/algo* */*/*/*.py` returns
no output any :smiley:

TODO: Fix E501 errors.
TODO: Fix stuff in `algorithms` subfolder

As part of http://24pullrequests.com/
Merge pull request #51 from habi/make_pep8_happy

Fixed PEP 8 coding style violations (all but E501)