Add OTP version R15 to allowed version regex
Add OTP version R15 to allowed version regex

amyvmiwei/riak,elkingtonmcb/riak,GabrielNicolasAvellaneda/riak,authbox-lib/riak,yangchengjian/riak,biddyweb/riak,xuejianhai/riak,basho/riak,DavidAlphaFox/riak,laurenrother/riak,glickbot/riak