(PDB-472) - Annotate MQ messages without parsing payload

Received time and a UUID are currently added to incoming (via HTTP) messages
before placing them on the queue. This commit adds those annotations to the
MQ message header no longer requires parsing the incoming message payload
before placing it on the queue.
Fixed a date related issue causing tests to fail (only at certain times
of the day)
Merge pull request #885 from senior/ticket/master/pdb-472-mq-pass-through

(PDB-472) - Annotate MQ messages without parsing payload
PDB-473 Support POST using application/json data in the body

This patch adds to the commands end-point the ability to simply POST using
application/json with the JSON content in the body.

It also switches the terminus to use this mechanism.

We found that the url encode/decode required to support x-www-form-urlencoded
was actually quite an overhead in a number of ways:

* The urlencode on the terminus added overhead
* The urldecode in the server added overhead
* The interim strings created during this encode/decode process can get quite
  large increasing the amount of garbage collection required

This feature has been implemented by providing a new middleware that will move
the body into the parameter :body-string of the request when the content-type
is not set to application/x-www-form-urlencoded. This provides a convenient
backwards compatible layer so that the old form url encoding can still be
supported for older versions of the API.

Signed-off-by: Ken Barber <ken@bob.sh>
PDB-473 Add a content-type verification middleware

Signed-off-by: Ken Barber <ken@bob.sh>
PDB-473 Additional tests for verify-content-type and other cleanups

Signed-off-by: Ken Barber <ken@bob.sh>
PDB-473 Convert submit-command-via-http! to use application/json POST

Signed-off-by: Ken Barber <ken@bob.sh>
PDB-473 Use (seq foo) on its own

Signed-off-by: Ken Barber <ken@bob.sh>
PDB-473 Adapt for new queue message format

PDB-472 changes the format of the messages received from the queue so that
headers are top-level. This patch just ammends the work to support that.

Signed-off-by: Ken Barber <ken@bob.sh>