Bug 37902: Apply exact match for datetime

Bug 37902: Apply exact match for datetime

We do not want to apply "like" and do a "contains" search if a correctly
formatted date is passed (ie. starting with "YYYY-MM-DD HH:MM:SS")

It causes underlying problems if we add '%' characters to this string as
it will then become an invalid date.

There are several ways of dealing with this problem. This patch is
suggesting the easiest path: Apply an exact search (ie. do not add '%')
if the value appears to be a datetime.

Certainly not the best looking patch but it seems to be quite effective:
  * no need to change the client
  * no need to rework build_query_params, merge_q_params, attributes_from_api

We could (to confirm) pass the result set, but it seems a lot of additional processing
(that is done later already, in attributes_from_api)

Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>