[#781] Begin improving IFacets docs

Better docstrings and an example extension for IFacets. Both still need
some work..
[#1350] resource format change
[#1332] Makes markdown link a popover with context of CKAN flavoured markdown
[#1330] Get user ids from a list of ids or names
[#1330] Filter activity from specified users
[#1330] Update documentation
[#1330] Use actual value of site_id for default
[#1330] Fix test failures
pep8 fix for test failure
Update action function and documentation

* Split the helper function into two functions.
* Add better docstrings.
* Improve the documentation and explain about site user.
Fix tiny error.
Enable `hide_activity_from_users` by default
Allow specifying user when creating a group using the factory

With this, we're able to create a group owned by a specific user.
new_tests.helpers.call_auth now work for any auth type (update, create, ...)
[#1505] Fix bug when non-sysadmins invited users to organizations

The problem was with the .user_invite() auth function. Instead of adding 'id'
to the data_dict, I was adding it to the context. Fixed now.

I've also changed it to require a data_dict, and a data_dict['group_id'] (as
they're required anyway).

While I'm at it, I rewrote the tests into the new testing style.
Merge branch 'master' into 1505-invite-to-organization-causes-error
[#1505] PEP8
new_tests.helpers.call_auth now uses logic.check_access
Instead of importing NotAuthorized in test helpers, do it on the test file
Change way to call nose's assert_raises, so it works on Python 2.6