Merge pull request #90 from abdulrauf/master

multiple asset category filter
Merge pull request #92 from abdulrauf/master

find_by_path or find_by_previous path fix
Merge pull request #94 from abdulrauf/publishing_authorisation

Publishing authorisation
Merge pull request #95 from abdulrauf/publishing_authorisation

Publishing authorisation fixes and also mixin manager for gluttonberg models
Merge pull request #98 from abdulrauf/publishing_authorisation

bug fix : contributor should only be able to delete their assets
Merge pull request #112 from abdulrauf/publishing_authorisation

parent_nav_li,  sub_nav_li classes for navigation_ul