TRQ-1260: qdel clientretry support

Added clientretry feature as it works in qsub:
* -b <num> command line argument support;
* CLIENTRETRY configuration option support;
* PBS_CLIENTRETRY environment variable support.
Clientretry allows try to connect to the server in a loop during the
given time period.

Added 3-times retry to send the general command (delete task) to the
server as it implemented in qsub, see TRQ-2417.

Added unit test.

Removed server code duplicate from qsub.
Merge pull request #247 from DSRCompany/TRQ-1260_qdel_clientretry_support

TRQ-1260: qdel clientretry support
TRQ-2736. Fix a host detection issue with pbsdsh/tm interface.

When using pbsdsh, fix assumptions where pbs_mom incorrectly determined
which host was being used. pbs_mom's checks didn't really work if you
are running more than one task per node at a time. This caused hangs
when running pbsdsh utilities.
Unit tests fixes

Unit tests passed on CentOS 6.5 with this fixes
TRQ-2761: prevent resetting last status sent timestamp to 0

If torque MOM needs to force status update message sending in some cases
(if if pass not more than 1/3 of configured interval) it moves the last
status sent timestamp so the next status update will be sent after 1/3
of the interval. In other cases (if it passed more than 1/3 of the
interval) mom resets the last status update timestamp to 0 that makes
impossible to determine the actual last message sent time.

Updated the forcing function algorithm to never reset the timestamp to
0. Now it just moves the last timestamp like it's time to send the
update (time_now - update_interval).
TRQ-2761: minor build fixes
TRQ-2761: Unit test
TRQ-2761: Minor: update a comment