Update for 19 (0x13) and 02 (0x02)

Could not find 19 (0x13) in the csv. But skipping over it for time delta appears to be correct.
Looks like 0x02 represents a weak signal (SensorWeakSignal)
did some tests to set time to decode the cgm
test to see how it saves changing multiple parts of the time.
Merge branch 'erobinson/cgm-decode' of http://github.com/erobinson/decoding-carelink into erobinson/cgm-decode