split client code into AMD modules and load them with requirejs

move templates into dedicated files and include those in the index te…

fixes #959

jscs plugins removed

Reduce opacity of trash and favourite icons

Replace tipsy with tooltip

Allow loading of multiple messages

Fix unit tests - mock IUrlGenerator

show sender avatar again.

set accountId and folderId on each message to fix unified inbox replies

don't show a placeholder if 'from' isn't set on the message

change attachment template to underscore template

Fix prefetching messages in background marking them as read

remove new uncached messages from folder list cache

fixes #952

cache new messages loaded in background