Rename mission files to challenge files
Merge branch 'master' of https://github.com/FirstLegoLeague/fllscoring

# By rikkertkoppes
# Via rikkertkoppes
* 'master' of https://github.com/FirstLegoLeague/fllscoring:
  refactored index filter a bit
  Move tests to a more descriptive folder structure
  Added spec for index filter