Removal of old files and update of assets and imports

Joint work with aab

- In the chat, when loading more messages, automatically scroll to the previous
oldest message instead of staying at the top;
- In the chat, don't use the event 'scrollTop < 50' to load more messages as
it won't work on mobile (all the webclient is scrolling, so the client action's
scrollTop will always be 0);
- Generalize the way to load more messages between chat and chatter by moving
the logic to the MailThreadMixin and creating a common template;
- Improve the style of this 'load more messages' button

Correctly send a notification on people invite
Also remove useless less rule

- DOM simplification
- LESS refactoring
- Unused code removal
- Integration in new design
- Fix a bug when trying to scroll the the last seen message in an empty channel
 (bug was due to the assumption that an empty jQuery element equals false,
 which is wrong)

Put 'More' actions in the Sidebar

This commit add instant messaging features in mail module to make it a real team collaboration tool. Lots of these new features will replace Timeleine view (which is not removed in this commit). Many files have been moved, split or created for a better structure.

- My Channels : A user can be member of channel (mail.channel). These are discussion group, but also an aggregate of notification. Setting a channel as document follower, it will receive all the message (of the chatter) in real time, as information stream.

- A new Inbox : this aims to replace the timeline view. The user will see its channels grouped by 'slot', and receive the message in real time. Jump to the form view, invite people, create private discussion group, talk directly to another employee, ... are the main features. Your message can still be starred. The 'Inbox' will only contain your needaction.

- Needaction concept : a needaction is a message calling you to do something. If you follow a document as a person, the posted message will be 'needaction' for you. It can also be a message where you are mention with a '@my_name' (this feature is not added in this commit).

- The chatter doesn't change so much. It still allow you to see the discussion about the document, to star some message, and treat your needaction.

- Chat : the only way to have a minified conversation is from the Inbox Client Action. It allow you to keep an eye on a channel when working on document.

- Compose Message : it is now common to the Inbox, and the chatter. It offers shortcode substitution, attachments management, and optional subtype.

- UI : the chat window has been clean, they have a new look now.

To do so,
- Chatter code have been completely rewrite, independently of timeline view
- Add 'bus' as mail dependency, to insure real time
- A mail.message is broadcasted on the bus channel (db, mail.channel, channel_id), and a channel header on (db, res.partner, partner_id)
- Extracting mail_thread mixin used for Chatter and ChatMailThread (Inbox client action). This uniformize the programming structure with the server side
- Clean CSS style and use LESS instead of CSS
- Define a new messafe format (message_format method in mail_message.py), compatible with fetching and broadcasting
- Apply guideline coding conventions

This commit also break the module im_livechat, since im_chat models don't exists anymore and will be fixed in the next commit.

Thanks to Thibault Delavallee (tde) for the long debates and precious advices, Richard Mathot (rim) for the support, Simon Lejeune (sle) for the client action layout, and the Usability Team (apr, lle, bst yti) for the long testing.

Conflicts:
	addons/mail/models/mail_thread.py