add MAPI over HTTP support

MAPI over HTTP is supported on at lease Exchange 2013 SP1
correct formatting
correct definition

the CAS-Array is the server we want to reach...
do not revert the round-robin patch 1bcfd29
offload the whole auth process onto a backend peer.

with squid-3.2+ you use login=PASSTHRU and *no* Squid auth setup
to offload the whole auth process onto a backend peer.
offload reverse auth to backend
Merge pull request #668 from trendchiller/master
fix bungled config

see https://forum.pfsense.org/index.php?topic=73301.msg424937#msg424937
Merge pull request #670 from trendchiller/master
Directive 'ignore_expect_100' is obsolete
Merge pull request #671 from trendchiller/master
Merge pull request #1 from pfsense/master

update fork
Bump version of recently updated PBIs
Bump versions for recently rebuilt PBIs
allow multiple CAS-servers, correct checks
allow multiple CAS-servers, correct checks
fixed reverse owa

OWA does not work with round-robin
enable AutoDiscover HTTP
add autodiscover url for self-hosted domains

as tested in microsoft-connectivity-analyzer
Merge pull request #675 from trendchiller/master