List actions and default messages

- Added list actions for contentlibrary, discussionslibrary, memberships and members
- Renamed participants to members
- Extended list options to take care of enabling and disabling of list option buttons and hiding and showing of list options.
- Added the ability to provide initial content in the infinite scroll plugin
- i18n fixes
- Default messages for contentlibrary, discussionlibrary, memberships, members and search

Note: This builds on top of #2816 and #2824