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
port disk_config API into v3 part1

This changeset only copies the v2 files into the appropriate v3
directories unchanged. The copy as-is will not be loaded by either
the v2 or v3 extension loaders. The second changeset will then
make the changes required for it to work as a v3 extension.

This is being tried in order to make reviewing of extension
porting easier as gerrit will display only what is actually
changed for v3 rather than entirely new files.

Partially implements: bp v3-api-extension-versioning

Change-Id: Ia2ef4ab8cb63878d16360378c61e5182f4593200
Remove redundant if statements in cells.state

Removed redundant if statements since checking if cell is None twice
was not intuitive.

Change-Id: I20d7ade5acd27d23ba53ef065d0e4d24218182c2
Merge "Sync v2/v3 console_output API extensions"
Merge "port disk_config API into v3 part1"
Merge "Remove redundant if statements in cells.state"
Merge remote-tracking branch 'm_src_repo/citrix-fixes' into build-temp