Use sequence numbers to order tuning files

[rbrott]

Latest tuning files are currently determined by mtime. That works fine with an updated clock, but that's really not right to assume for RC devices. Sequence numbers should be used to order the files with timestamps left purely as a hint for users.

To check if you have this problem, download the latest tuning file from the page, run the tuner again, and download the latest file again. If the timestamps for the two files match, something has gone wrong with the clock and you should remove those files. Tuning files are stored under /sdcard/FIRST/RoadRunner/tuning/.