Allow Composet to automatically reply from the Runbox global domain used for a username without the need to set up an identity

[runboxdave]

Customers can use any of our global domains with a username or alias. However, if they register on a website using one of these domains and mail then comes to their Runbox account they would need to set up an Identity for each of the domains used with an alias identity or their main account identity for this to work as a from address when they reply to the message.

A useful solution to this would be to allow Runbox 7 to reply from the address that the message was sent to without the need for an identity to be set up as long as the address it is sent to is an alias or main username on one of our global domains.

[castaway]

Notes on how to do this:

compose/draftService "fromsSubject" is generated from profileService.validProfiles, if the user is not using virtual domains, also generate username@runboxdomains (global_domains is in profileService), and add that to fromsSubject as well