Sync v2/v3 console_output API extensions

Synchronises changes made to the v2 version of the console_output
API extension to v3 in commit c651f4928c65407cff86a9f9efc046a0f76a9519
which fixed bug  #1194032

Partially implements blueprint nova-v3-api

Change-Id: Ie28d771d25636decb7b1f17756654be56762b35f
Merge "Sync v2/v3 console_output API extensions"