TSA Pixel Tracking V2: Extra Sources Created For 'refcd' values w/unknown distribution short-code

Pixel playback will create a new source row in the `st-tracker`.sources table when a 'refcd' with an unknown short-code is encountered. This occurs once per pixel log file for each such 'refcd' value.

Steps to reproduce:

1) Create a pixel log file for Martian Tourism, accountID 541, siteID 560, with one valid pixel hit having a 'refcd' field that has a value of: ZY00001s_Fake_Keywords (the important thing is that the first two characters do not map to a known distribution)

2) Issue a query against the proper database instance for accountID 541:

select * from `st-tracker`.sources where accountID=541 and altKey='ZY00001s_Fake_Keywords'

Assuming the first run through, then this select will return an empty set.

3) Process the pixel log file through v2 pixel playback

4) Issue the query from step #2. This time a single row should be returned.

5) Create a second pixel log file for Martian Tourism, again with a single pixel hit having a 'refcd' field that has a value of: ZY00001s_Fake_Keywords. Be sure to set the time stamp of the log line ahead of the time stamp from the first file.

6) Process the second pixel log file through v2 pixel playback

7) Issue the query from step #2. This time the result set will return 2 rows, when in fact it is supposed to return only 1 row.

Subsequent runs will always increase the source row count by 1 more row (regardless of how many times the refcd value appears in a file, it will increase by 1 only for each file processed).