pqm error formatting

[Robert Collins]

PQM appears to be happily running the new attachment based code;
thanks for everyones patience in getting this available ;)

What this means is:
 - pqm will now send two gz attachments when merge files, one with
stderr and one with stdout.
 - the body of the email contains a subunit-filter | subunit2pyunit
processed body of stdout, in particular it currently shows skips and
perhaps we want to remove them.
 - it appears to (now) be free of unicode confusion and stdout/stderr
confusion : at least in my tests its quite reliably spitting an error
stream at me which 'gunzip -c | subunit-stats' can handle happily:

Total tests:   24093
Passed tests:  22010
Failed tests:      1
Skipped tests:  2082
Seen tags:

We have as part of this deployed a slightly tweaked testtools - r70 of
trunk, and bzr 2.1.2 for pqm to use.

Cheers,
Rob