Provide failsafe for a client's name

It is possible that a recipient received and processed by the system may not
have a name set. In that case, the email mailbox should be used. As a
failsafe, avoid crashing if the User::save() should fail.
Don't clobber custom data for new clients
Add import feature to user directory and organization
Fixup user import via cli
orm: Make __get() and get() consistent
Fallback to client email display on user directory
Simplify header detection logic with outdent
Merge pull request #790 from greezybacon/feature/user-import

Reviewed-By: Peter Rotich <peter@osticket.com>