Assorted fixes and new features for support request app:

Features

• post are now HTML and use the preferred editor ( CKEditor by default )
• posts are ingested in Web Message and the app uses same data model as erp5_crm ( so it is able to display support request created with "standard" ERP5 interfaces)
• date of post uses momentjs relative time (New message by Bob 1 hour ago...)

Bug fixes:

• post API no longer use proxy roles / immediate reindex
• RSS was re-implemented to list events. The previous approach of listing support requests had an issue that the date of new posts was still the date of the original support request.
• attached files to the "submit new support request" dialog where not uploaded
• using a handlebars template we prevent html injection / XSS
• increased test coverage