* Rename classes and files to match model names, and removed workflow engine.
* Some fields should be readonly if not in draft.
* Allow Knowledge / Manager to edit previous history names and summary
* Improve ux by adding user_has_drafts to document pages.
* Changes because of implementation of active field on document_page
* Add ir.rules for document.page.history
* Allow to quickly cancel&draft from 'to approve' state
* FIX BUG: am_i_approver was being run as sudo(), hence always giving the user Approving rights.
* FIX hooks
Because of default='draft' on the state field, state IS NULL wasn't selecting anything.
Left the condition in case this is changed in the future.
[IMP] - Improved views to match document_page improvements.
[IMP] - Added notification to followers when a new version is approved.
[ADD] - Updated document_page_approval pot and added es translations.
[IMP] - document_page_approval: Updated spanish translation.
