model/competition: Added participants attribute to CompetitionClass model
Removed repoze.what dependency

TurboGears 2.2 has that functionality built-in now
Upgraded repoze.who to v2.1
Removed tg.devtools dependency
Merge pull request #49 from Turbo87/repoze-what

Removed repoze.what dependency
Merge branch 'master' into competitions