New spec implementation for the cli

[sergiusens]

This implements the move to the new spec'ed cli, also using docopts instead of argparse.
The integration tests are now also python based instead of using plainbox

[elopio]

👍 Merge!
A huge change right at the end of the year, what could possibly go wrong? ^_^.
Next year we can focus on making the coverage more meaningful. For now it's good enough.
I'll let @kyrofa hit the Merge button, so the three of us get an equal share of responsibility when things terribly break ;)

[kyrofa]

Haha, @elopio you suck. Merging!