Avoid passing more than one instance of ERL_LIBS to child processes
Avoid passing more than one instance of ERL_LIBS to child processes

This commit fixes issue #98 by removing the ERL_LIBS and REBAR_DEPS_DIR
from the list of environment variables exported by the rebar_port_compiler
plugin.

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