Add russianroulette.{pm,yml}

Behaviour modified from previous. No longer reports ``remaining''
unchecked barrels, barrels are fired in sequence after a random barrel
is chosen following a successful shot.
Add rr alias for russianroulette command
Fix uninitialised variable in russianroulette.pm
Fix typo in russianroulette.pm

s/get_config/config_get/ durr...
Merge branch 'feature/russianroulette' of https://github.com/tlcine/odchbot into tlcine-feature/russianroulette
Added in a schema for russianroulette to autoinstall its own variable
and removed the one left in odchbot.yml.example