Remove warnings_as_errors from rebar.config
Remove warnings_as_errors from rebar.config

rebar's beam files are actually compiled by bootstrap's call to
make:files/2, so warnings_as_errors in rebar.config isn't really used.

dcarastan/rebar,norton/rebar,RubberCthulhu/rebar,lrascao/rebar3,project-fifo/rebar3,syl20bnr/rebar,jacktang/rebar,matwey/rebar,oubiwann/rebar,RubberCthulhu/rebar,walrusVision/rebar3,shkumagai/rebar,project-fifo/rebar3,lrascao/rebar,shkumagai/rebar,blt/rebar3,bsmr-erlang/rebar,lrascao/rebar,SiDen/rebar,norton/rebar,apache/couchdb-rebar,dcarastan/rebar,CMoH/rebar,matwey/rebar,GabrielNicolasAvellaneda/rebar,norton/rebar,norton/rebar3,beni55/rebar,ferd/rebar3,evnix/rebar,matwey/rebar,lrascao/rebar,sile/rebar3,blt/rebar3,processone/rebar3,syl20bnr/rebar,syl20bnr/rebar,rebar/rebar,choptastic/rebar,cloudant/couchdb-rebar,saleyn/rebar3,platinumthinker/rebar,jacktang/rebar,tsloughter/rebar3,benoitc/rebar3,paulo-ferraz-oliveira/rebar,cloudant/couchdb-rebar,lpgauth/rebar,matwey/rebar,rebar/rebar,beni55/rebar,sile/rebar3,scatterbrain/rebar,cloudant/couchdb-rebar,platinumthinker/rebar,platinumthinker/rebar,norton/rebar,kellymclaughlin/rebar3,surik/rebar3,walrusVision/rebar3,CMoH/rebar,SiDen/rebar,matwey/rebar,CMoH/rebar,bsmr-erlang/rebar,lrascao/rebar,rebar/rebar,K2InformaticsGmbH/rebar,fauxsoup/rebar3,SiDen/rebar,benoitc/rebar3,fishcakez/rebar3,vladdu/rebar3,K2InformaticsGmbH/rebar,K2InformaticsGmbH/rebar,paulo-ferraz-oliveira/rebar,K2InformaticsGmbH/rebar,bsmr-erlang/rebar,scatterbrain/rebar,GabrielNicolasAvellaneda/rebar,zugolosian/rebar3,csyangchen/rebar,macintux/rebar,GabrielNicolasAvellaneda/rebar,csyangchen/rebar,jacktang/rebar,rebar/rebar3,beni55/rebar,surik/rebar3,apache/couchdb-rebar,choptastic/rebar,zugolosian/rebar3,oubiwann/rebar,erlang/rebar3,csyangchen/rebar,K2InformaticsGmbH/rebar,macintux/rebar,bsmr-erlang/rebar,scatterbrain/rebar,djnym/rebar3,fabiankrol/rebar3,fabiankrol/rebar3,choptastic/rebar,lpgauth/rebar,apache/couchdb-rebar,oubiwann/rebar,dcarastan/rebar,lpgauth/rebar,evnix/rebar,shkumagai/rebar,fauxsoup/rebar3,linearregression/rebar3,paulo-ferraz-oliveira/rebar,macintux/rebar,linearregression/rebar3,evnix/rebar,lrascao/rebar,processone/rebar3,jbalint/rebar3,rebar/rebar3,jbalint/rebar3