[FIX] web: add missing icon, add warning, fix deferred

* ir_actions_common should return a deferred : some widgets
  do not return a deferred in start, so it could be undefined.
  it now is always a deferred.
* add icon for diagram view + breadcrumb support. diagram view
  is so rare that it wasn't tested in the client refactoring.
  This patch adds an icon for diagram view, and better support for
  breadcrumbs
* add warning in debug mode print workflow: when no record is
  selected, display a warning instead of failing silently
[IMP] project,project_issue: follow tasks and issues that are ready for the next stage
[FIX] website: Odoo's social URLs
[FIX] website: typos
[REM] db_manager: remove old dependencies to datejs and timepicker and replace by momentjs
[IMP] website_forum: better implementation of automatic nofollow attribute
on links in forum posts.

This is now done when creating / updating posts instead of updating the display
of the post. This means that old posts may contain nofollow attribute altough
the user has sufficient karma; however it is acceptable compared to the computation
we save by avoiding processing every post to display.
[IMP] ir.attachment : move the fields index_content (from document), mimetype and datas_checksum (from website) to base. In base, the mimetype is computed with the Magic python lib (if installed, else with a custom function using magic number), and the index_content is an implementation of strings unix command. In document, index_content is still computed with the indexer of document module.
[IMP] website_twitter: authentication error popup with proper description base on twitter error code and responses