Fix problem with millisecond timestamps previous to 2002 being rejected due to
a bad comparison.
Update unit tests to validate more timestamps.

Signed-off-by: Chris Larsen <clarsen@euphoriaaudio.com>
Fix for #256 where variable-length integers were not parsed correctly when
being emitted to RTPublisher plugins. Thank you @zackurey!

Signed-off-by: Chris Larsen <clarsen@euphoriaaudio.com>