Make sure code is PEP8 compliant

Related to #178

In cases where we actively violate PEP8, we should have our own custom pylintc (e.g.).

Both pep8ify and pyfmt will rewrite code to adhere.

They both seem to be unsure of themselves when it comes to maximum_line_length.

After running, it'd be smart to check with git diff --color-words locally. Luckily GitHub also now has nice word highlighting in diffs.

@tseaver

As an experiment I tried to get datastore/entity.py to conform. Notice that #188 has come up as an issue in f7de067 since the linter is fooled about the type of self.key().

@tseaver Can you take a look and let me know what you think?

Some notes:

Neither pep8ify nor pyfmt properly indent docstrings
pyfmt is much slower than pep8ify (at least on the first run)
pylint -E <file> only checks errors
pylint --reports=n <file> only shows the offending lines
All PyLint codes: http://pylint-messages.wikidot.com/all-codes

To get just the errors and the global evaluation score

pylint --disable=RP0001,RP0002,RP0003,RP0101,RP0401,RP0402,RP0701,RP0801 <file>

Adding color pylint --output-format=colorized

I spent way too much time hacking on the ast but have a decent hack which I think will do the part missing in pep8ify, which is correct indenting of docstrings:
https://gist.github.com/dhermes/85c3a3a464d2cff312ea

I have two more branches:
https://github.com/dhermes/gcloud-python/tree/pep8ify-gcloud-dir
https://github.com/dhermes/gcloud-python/tree/pep8ify-setup

UPDATE:
I destroyed these branches by changing the gcloud-dir one into an upstream branch of the four indents PR (#207) and merging the setup one into the same PR.