Update version number for 2.1b
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
[#715] Tweaks to  method
[#715] Remove helper and do work in controller and minor tweaks
[#715] Fix can_be_previewed for embeds etc
[#715] Further cleanups
[#792] Fix auth function
[#792] Fix package_create auth function for sysadmins
[#792] Fix some tests now auth changes made
[#729] Slight code refactor
[#1056] Fix for 500 error on group create page

Also fixes for:
* Group/Org edit template: added missing context in sidebar
* Group/Org new template: added missing helper text
* Small template refactors: moving group context info into snippet and also
group/org helpers into snippets
package_list performance fix
package_list: return sorted by name
fix for package_list returning nested list
package_list: use context['model'] instead of import, from @tobes
Rebuild CSS
[#1025] User log in/out fixes including i18n and non standard root url
[#1025] Fix failing tests due to extra redirect etc (stupid tests)