The calculated minimum lost packets represents the lowest number of
lost packets missed during an RTCP report interval. Zero of course
is the lowest, but the idea is that this value contain the lowest
number of lost packets once some have been missed.

This patch checks to make sure the number of lost packets over an
interval is not zero before checking and setting the minimum value.

Also, this patch updates the rtp lost packet test to check for
packet loss over several reports vs one.

Change-Id: I07d6e21cec61e289c2326138d6bcbcb3c3d5e008

Now that both FIR and REMB are being sent in compound packets
these tests can be enabled.

This also extends the REMB nominal test to cover the REMB
contents itself.

Change-Id: Ibfee526ad780eefcce5dd787f53785382210024a

Added unit tests for RTCP video stats. These tests include NACK, REMB,
FIR/FUR/PLI, SR/RR/SDES, and packet loss statistics. The REMB and FIR
tests are currently disabled due to a bug. We expect to receive a
compound packet, but the code sends this out as a single packet, which
the browser accepts, but makes Asterisk upset.

While writing these tests, I noticed an issue with NACK as well. Where
it is handling a received NACK request, it was reading in only the first
8 bits of following packets that were also lost. This has been changed
to the correct value of 16 bits.

Also made a minor fix to the data buffer unit test.

Change-Id: I56107c7411003a247589bbb6086d25c54719901b