Bump Ansible requirement to 1.6
Bump Ansible requirement to 1.6

debconf module is used in ferm role which does not exist until 1.6

Twansparant/trellis-db-sync,jwall/trellis,jwkicklighter/trellis,cimocimocimo/cimo-wordpress-server,rogeruiz/trellis,mAAdhaTTah/bedrock-ansible,fullyint/trellis,jeffstieler/bedrock-ansible,ChilliCreative/trellis,louim/bedrock-ansible,webdev1001/bedrock-ansible,ChilliCreative/trellis,ckovey/trellis,ckovey/trellis,proteusthemes/pt-ops,windeck/ansible-bedrock,afonsoduarte/ansible-stacey,all9lives/trellis,drewrawitz/wp-ansible,dmin7b5/trellis,alan-c/trellis,fullyint/trellis,Twansparant/trellis-db-sync,drawcard/trellis,dboune/trellis,erikbelusic/trellis,alan-c/trellis,partounian/trellis,NicBeltramelli/trellis,all9lives/trellis,kalenjohnson/trellis,enricodeleo/bedrock-ansible,pressbooks/trellis,BrandonShutter/trellis,BrandonShutter/trellis,austinpray/bedrock-ansible,kalenjohnson/trellis,cimocimocimo/cimo-wordpress-server,dboune/trellis,Twansparant/trellis-db-sync,afonsoduarte/ansible-stacey,cimocimocimo/cimo-wordpress-server,skynet/trellis,NicBeltramelli/trellis,jeffstieler/bedrock-ansible,buluma/trellis,rpkoller/trellis,patrickheeney/trellis,dailysecret/trellis,newtonne/trellis,NicBeltramelli/trellis,NicBeltramelli/trellis,pressbooks/trellis,fusionpig/trellis,partounian/trellis,buluma/trellis,jvandijk/epwp-trellis,ThemeSurgeon/trellis,evanfuture/trellis,bbttxu/trellis,buluma/trellis,mAAdhaTTah/bedrock-ansible,fullyint/trellis,roots/bedrock-ansible,newtonne/trellis,roots/trellis,roots/trellis,SecureCloud-biz/trellis,jvandijk/trellis,kalenjohnson/trellis,partounian/trellis,roots/bedrock-ansible,kulturavashchi/trellis,mAAdhaTTah/bedrock-ansible,buluma/trellis,cimocimocimo/cimo-wordpress-server,Seravo/wp-vagrant,kalenjohnson/trellis,merchantguru/trellis,jvandijk/epwp-trellis,dailysecret/trellis,mlaa/trellis,fullyint/trellis,mAAdhaTTah/bedrock-ansible,mlaa/trellis,Seravo/wp-palvelu-vagrant,Twansparant/trellis-db-sync,JacobDorman/bedrock-ansible,creditera/trellis,proteusthemes/pt-ops,jeffstieler/bedrock-ansible,proteusthemes/pt-ops,partounian/trellis,newtonne/trellis,brettwise/bedrock-ansible