activesync fake-server creator can specify debug mode

Figuring out what's up with ActiveSync fake-server issues or just ActiveSync
in general can be confusing.  The problem in this case turned out to be a
Gecko regression (and necessitated use of wireshark to further diagnose), but
this is still useful.
Merge pull request #23 from asutherland/improve-activesync-debugging

activesync fake-server creator can specify debug mode.  This will only be put into use as part of the review for https://bugzil.la/1070429