provision/deploy: created deploy interface
provision, testing: added Deploy function in Provision interface

Also created related functions in interface implementations.
app/writer.go: creating and using Logger interface to write logs
provision,testing: receiving io writer on deploy function
provision/juju/provisioner: implementing deploy action
provision, testing: Adding methods needed to implement Unit interface from repository

Also adding methods that the deploy method calls, e.g.: InstallDeps and
Restart
repository/repository: commenting unit command call to not loose the thought