TSA Pixel Tracking V2: v2pixsync.sh can overwrite a pre-existing pixel log file

If the v2pixsync.sh script is run multiple times within an hour, then the final filename will be the same for each run, which could lead to the second run overwriting the file created on the first run.

Instead that condition should be detected, and the second file should be 'revisioned' so as not to have a name collision. E.g. if the v2pixsync.sh is run a second time for site 699, it could want to create a file named: 2011-10-31-0400.tsv.gz - but if one is already present then it should create a file named 2011-10-31-0400_1.tsv.gz instead. If run a third time, then a file named 2011-10-31-0400_2.tsv.gz should be produced.

The script will need to be updated, and the playback code will need to be updated to allow for these revisioned files to be found, and played back (and in the correct order). The base file should be played back first, with the revisioned files played back in the same order as their revision #