api/app: make bucket and access key channels asynchronous
api/app: make bucket and access key channels asynchronous

It prevents those two go routines from blocking forever.

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