Post deployment commands

[Charles Butler]

Post deployment, amulet needs to proxy juju commands for removing relations, destroying services, exposing, and adding/removing units

[Marco Ceppi (marcoceppi)]

This should be transparent to the user.

// These create deployer file
d.add('mysql')
d.configure('mysql', {options})

d.setup()

// This will use juju set mysql from command line
d.configure('mysql', {new_optoins})
d.add_unit('mysql')

[Marco Ceppi (marcoceppi)]

Blocked until jujuclient becomes py3 compatible