overide igc validation

[kuaka]

In the case that an IGC file is not valid (parsing con-fig check) a score keeper should seek a backup track from pilot. If not available as it stands if he/she wants to use the igc anyway he can alter the parsing con-fig for the comp-> submit track-> change parsing con-fig back. It would be useful to have an easier override for an individual track (probably by forcing the parsing con-fig in back end in this case)
However we probably only should be doing this in the case that it is an altitude problem. Other things that the igc_lib checks (with parsing con-fig) include big time gaps in the igc, very short igc files etc... having an override to allow big gaps in igc files would be counter productive to fair scoring. (and altitude problems would need to be overridden only if we were not checking airspace or it was clear pilot couldn't have violated airspace.

[kuaka]

confirmed that this needs to be implemented.

[kuaka]

closed with 9b6a290.
Not deleting branch at the moment as may be needed for LP branch (if not forked)