provision/docker: correctly return last error in auto scaler
provision/docker: correctly return last error in auto scaler

Endika/tsuru,firebitsbr/tsuru,gwmoura/tsuru,ggarnier/tsuru,tsuru/tsuru,gwmoura/tsuru,jblancett/tsuru,ggarnier/tsuru,guilhermebr/tsuru,ArxdSilva/tsuru,cgvarela/tsuru,kgrvamsi/tsuru,gciotta/tsuru,RichardKnop/tsuru,guilhermebr/tsuru,Endika/tsuru,mderaldo/tsuru,mderaldo/tsuru,RichardKnop/tsuru,gciotta/tsuru,tsuru/tsuru,tuxmonteiro/tsuru,ArxdSilva/tsuru,kgrvamsi/tsuru,tsuru/tsuru,tuxmonteiro/tsuru,4eek/tsuru,RichardKnop/tsuru,hcxiong/tsuru,firebitsbr/tsuru,tuxmonteiro/tsuru,cezarsa/tsuru,jblancett/tsuru,4eek/tsuru,Endika/tsuru,cgvarela/tsuru,cgvarela/tsuru,cezarsa/tsuru,4eek/tsuru,tsuru/tsuru,ArxdSilva/tsuru,guilhermebr/tsuru,gwmoura/tsuru,firebitsbr/tsuru,mderaldo/tsuru,hcxiong/tsuru,ArxdSilva/tsuru,kgrvamsi/tsuru,gciotta/tsuru,ggarnier/tsuru,cezarsa/tsuru,hcxiong/tsuru,ggarnier/tsuru,guilhermebr/tsuru,cezarsa/tsuru,jblancett/tsuru