Changes to allow Live Listener to replay historic data from SMS

This is just the first cut - few more minor changes are still needed.

Refs #6661
GUI changes to the StartLiveData dialog

Changed the layout of the radio buttons, added "UTC" to the absolute
time label and added code to limit the times the edit box will accept

Refs #6661
Fix GUI problems in RHEL 6 builds

The previous GUI changes used a function that wasn't available in the
version of Qt that comes with RHEL6.

Refs #6661
Change handling of RunStatus packets

Refs #6661
Add code to validate requested start time for live listener

Added code to LoadLiveData.cpp to validate the time string for the
requested start time.  Also use the epoch time for the "start from
now" option (instead of using the current time).  The epoch time gets
converted to 0 when passed to SMSD and SMSD handles that a little more
efficiently than passing it the current time.

Refs #6661