updated ratings (especially market value and age)
frontend: added "Documentation" page and renamed "Technical Details" to "Overview"
added option to use real match data for some matches (only unknown matches will then be simulated); also corrected rounding error with tournament amount
backend: fixed entering of (real) group phase matches; automatically invalidate simulation cache when new matches are available
simulator: made some necessary adjustments for the competition
Merge branch 'master' of github.com:walachey/football-worldcup-simulator into competition_2014