Update pilotCommands.py

This replaces the regular expression '.cfg&' for the extra options file names test (which would match files with "cfg&" anywhere in them) with a test for the suffix ".extra.cfg" and uses the contents of the files rather than the name of the files as the extra options. I've also placed these extra options at the start of the generated options, as some (eg -o CEType) don't work if placed at the end. This functionality is useful for testing and up to now I was using it for the LHCb VMs (to specify the glexec CEType and to force stop on failure.)
I do not understand this fix. Should it be just:
  if os.path.isfile( cfg ) and cfg.endswith( '.cfg' ):
     extraCFG.append( cfg ) 

extraCFG assumes to contain a list of file names. Replacing it by the contents of the files will not work. What am I missing ? Why you use .extra.cfg suffix instead of .cfg - is it a convention defined somewhere ?