collector: improve logging on MessageHandler
collector: improve logging on MessageHandler

Related to #203.

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