Add support for non-anonymous supportclients.

Introduced the 'treat as supportclient' permission. If the user has this
permission, their incoming emails are expected to be support requests and
the 'owner-email' attribute is filled in the issue.
The  'treat as supportclient' is added to the 'Anonymous' role by default
(can be removed to avoid receiving support from unknown emails).
fix merge conflict
Merge branch 'orchitech-feature1-permission'