add aarch64, arm, armhfp to the list of allowed arches for tasks

This corresponds to commit 589e0d49 in rhts.

Bug: 1092758
Change-Id: If7c8fed72dad1b51fdc7ed58d4e59fb4cef79aac
bkr policy-list needs to log in, in order to see private systems

Bug: 1087727
Change-Id: Ifb9ee631c9d34ff240a5fe995a12941e996a1648
LDAP queries need to be encoded as UTF-8

Bug: 1086505
Change-Id: I35ce938da135937d35f40df18ef0b05b6db1fd92
strip username, display name, and e-mail address fields

Now values consisting of only whitespace will not be accepted, since
they count as blank after stripping.

Bug: 997830
Change-Id: Id69e5fd2ec86e2a688631826c1bc9e66b32d6157
Merge branch 'release-0.16' into develop