Fixed lp:1395081 - do not bring any extra NICs on boot in MaaS
Increment juju to 1.20.13
Merge pull request #1208 from dimitern/lp-1395081

Fixed lp:1395081 - do not bring any extra NICs on boot in MaaS

This is a regression from 1.20.11, where juju did not try to bring all
interfaces up on boot (the same behavior as it is in 1.21+).

Changes that led to this issue were in part due to #1062.

(Review request: http://reviews.vapour.ws/r/518/)