Rename Pep8 and Pep257 Hooks

[proinsias]

The pep8 and pep257 projects have been renamed to pycodestyle
and pydocstyle, respectively.

To reflect these changes:

• The references to the former projects in README.md and default.yml
  have been updated.

• The ruby files under pre_commit for the former projects have been
  kept for backwards compatibility with existing .overcommit.yml
  files.

• New ruby files have been created under pre-commit.

[trotzig]

Thanks @proinsias! Instead of just keeping the old files, would it make sense to have them call the new classes?

[proinsias]

@trotzig – so that an existing .overcommit.yml with a Pep8 section would result in overcommit calling pycodestyle? I was assuming that the user might not have pycodestyle installed yet, but would likely still have pep8 installed.

[trotzig]

I was thinking we could just inject the name of the binary to some shared code. But yeah, probably not worth the effort.

One thing we could do is to add a comment in the default config at the place for the old hooks to mention that they are deprecated.

[trotzig]

The appveyor failure looks unrelated to your change. @sds, looks like it could be failing because of changes you made to LineEndings in afdebb. Do you have any ideas?

[proinsias]

@trotzig – I've added comments to the default config as requested.

[trotzig]

Thanks!

[sds]

@trotzig I don't have access to a Windows machine to look into that failure, but given the test that's failing is for a pretty minor feature, I've changed it to not run on Windows environments for now (see d446314).