linters: PEP257 support.

Signed-off-by: Yoan Blanc <yoan.blanc@cern.ch>
hooks: commit_msg_hook fix.

Signed-off-by: Yoan Blanc <yoan.blanc@cern.ch>
global: PEP257 formatting conformance.

Signed-off-by: Yoan Blanc <yoan.blanc@cern.ch>
Merge pull request #28 from greut/pep257

PEP 257 support and conformance.