Check if bridge exists and make sure it's UP in ensure_bridge

Introduce _bridge_exists_and_ensure_up that checks if the bridge
exists and if it's DOWN sets it UP

Change-Id: Ide9d2bb04016cadb347b00cadbee7007e61bd01e
Closes-bug: #1282741
Imported Translations from Transifex

Change-Id: I35cb53cb3a7a5c151c20be1d6ab7b7447e5c22d1
Merge "Imported Translations from Transifex"
Merge "Check if bridge exists and make sure it's UP in ensure_bridge"