Add coding standards to CKAN docs

[icmurray]

• [ ] Write up python coding standards as discussed at dev-meetup into CKAN docs. (Mostly written-up as part of dev-meetup notes.)

• [ ] Collate frontend coding standards (​http://aron.github.com/ckan-style/styleguide/) into same doc(s).

[seanh]

Please add to the file started to doc/coding-standards.rst

Also, for the Python coding standards see ​http://wiki.okfn.org/Coding_Standards as a starting point

[seanh]

I've also added the commit message guidelines as they reference a trac plugin I'm going to get installed.

I'll leave the rest to you.

I remembered that ​http://wiki.ckan.org/Main_Page has a bunch of pages under Developer Resources that should probably be updated and merged into these coding standards and deleted from the wiki