oauth_client: fix omniauth-oauth2 version
oauth_client: fix omniauth-oauth2 version

See https://github.com/intridea/omniauth-oauth2/issues/81

alexandreab/noosfero,larissa/noosfero,samasti/noosfero,evandrojr/noosfero,marcosronaldo/noosfero,CIRANDAS/noosfero-ecosol,AlessandroCaetano/noosfero,marcosronaldo/noosfero,marcosronaldo/noosfero,vfcosta/noosfero,blogoosfero/noosfero,blogoosfero/noosfero,tallysmartins/noosfero,coletivoEITA/noosfero-ecosol,vfcosta/noosfero,LuisBelo/tccnoosfero,larissa/noosfero,AlessandroCaetano/noosfero,larissa/noosfero,marcosronaldo/noosfero,macartur/noosfero,vfcosta/noosfero,evandrojr/noosfero,CIRANDAS/noosfero-ecosol,coletivoEITA/noosfero-ecosol,evandrojr/noosfero,tallysmartins/noosfero,samasti/noosfero,alexandreab/noosfero,tallysmartins/noosfero,blogoosfero/noosfero,LuisBelo/tccnoosfero,samasti/noosfero,CIRANDAS/noosfero-ecosol,LuisBelo/tccnoosfero,coletivoEITA/noosfero-ecosol,blogoosfero/noosfero,samasti/noosfero,LuisBelo/tccnoosfero,vfcosta/noosfero,alexandreab/noosfero,coletivoEITA/noosfero-ecosol,macartur/noosfero,coletivoEITA/noosfero-ecosol,evandrojr/noosfero,alexandreab/noosfero,larissa/noosfero,AlessandroCaetano/noosfero,marcosronaldo/noosfero,coletivoEITA/noosfero-ecosol,AlessandroCaetano/noosfero,larissa/noosfero,larissa/noosfero,AlessandroCaetano/noosfero,CIRANDAS/noosfero-ecosol,blogoosfero/noosfero,AlessandroCaetano/noosfero,marcosronaldo/noosfero,macartur/noosfero,samasti/noosfero,tallysmartins/noosfero,alexandreab/noosfero,CIRANDAS/noosfero-ecosol,alexandreab/noosfero,macartur/noosfero,LuisBelo/tccnoosfero,tallysmartins/noosfero,larissa/noosfero,evandrojr/noosfero,macartur/noosfero,macartur/noosfero,blogoosfero/noosfero,evandrojr/noosfero,marcosronaldo/noosfero,evandrojr/noosfero,AlessandroCaetano/noosfero,tallysmartins/noosfero,LuisBelo/tccnoosfero,macartur/noosfero,alexandreab/noosfero,samasti/noosfero,blogoosfero/noosfero,tallysmartins/noosfero,vfcosta/noosfero,vfcosta/noosfero