Test to find undocumented action functions
Documentation for member_roles_list
Fix import for asbool
Merge branch 'master' into 646-undocumented-action-functions

Conflicts:
	ckan/logic/action/create.py
	ckan/tests/logic/test_action.py
Document group_member_create
Added documentation for group_member_delete

Updated documentation for group_member_create
[#709] Document pckage_relationships_list()
Merge branch 'master' into 646-undocumented-action-functions
Add docstrings for two more functions

* Add docstring for organization_member-create.
* Add doctstring for organization_member_delete.
Remove tests for docstrings
Remove fixed functions from the blacklist
[#646] Add type. Fix username param

* Add type to all the function parameters.
* Refer to function with `func`.
* Fix _group_or_org_member_delete to use username instead of user_id
  so it's consistent with the other functions.
[#646] Make username change backwards compatible
[#646] Minor edits to some docstrings

Minor edits to some action function docstrings:

- Full stops (see docstring standards)
- a -> an
[#646] Clean up docstrings for member_roles_list
[#646] Tweak member_roles_list docstring
Merge branch 'master' of github.com:okfn/ckan into 646-undocumented-action-functions
Merge branch '646-undocumented-action-functions' into release-v2.1
[#715] Checks if resource can be previewed and that changes the UX

Adds new helper function to check if a resource can be previewed and adds it to
the templates.
[#715] Adds more logic to the  helper