[#6694] ticket:461 Form to send message to a user
[#6694] ticket:461 rewrite html form as widget
[#6694] ticket:461 Check that both users have email
[#6694] ticket:461 If there is one receiver, use his address in 'To:'
[#6694] ticket:461 Fix test
[#6694] Refactoring and cleanup

Signed-off-by: Tim Van Steenburgh <tvansteenburgh@gmail.com>