Fixed: back-action in searches with 1 result.

This fixes bug#8991.
http://bugs.otrs.org/show_bug.cgi?id=8991

If a search result finds just one ticket, it opens the ticket
directly instead of presenting the single result.

This is helpful, but sometimes you want to go back to the search
result to for instance click 'Change Search Options'. The
Back button in the ticket zoom did not work properly in this
scenario. This small patch fixes the problem.
Allow to set 0 TimeUnits in TicketCreate WS

If Ticket::Frontend::NeedAccountedTime is enabled, a time unit MUST be
specified before being able to create a ticket.

Currently, you can not set the TimeUnit to '0'; this fixes it.
I would consider it even better if the web service would use
a default of '0' if no value is passed.

This is also because the TimeUnit is only required in the Agent
Interface, for Agent articles; and with the TicketCreate web service
you can also create customer (or system) articles.
Tidy up UserSearch()

The result of UserSearch was previously not documented.
Also, the hash returned contained the ID as key and as value
it had some user fields, separated by spaces, which was not useful.

It also incorporates the changes from
http://bugs.otrs.org/show_bug.cgi?id=4723 -
"Useless substitution in UserSearch()".
Merge branch 'timeunit-ticketcreate-webservice' of https://github.com/mbeijen/otrs
Merge branch 'user4723' of https://github.com/mbeijen/otrs
Merge branch 'bug-8991-single-searchresult-back' of https://github.com/mbeijen/otrs
Updated CKEditor to version 4.3.
Updated changelog.
Use JSON::PP on PerlEx to prevent server errors.

JSON::XS is broken when run on PerlEx.
This change forces the JSON backend to use JSON::PP even when
JSON::XS is available, when run on PerlEx.

Fixes http://bugs.otrs.org/show_bug.cgi?id=7337
Merge remote-tracking branch 'upstream/master' into otrs-master