xenapi: move find_vbd_by_number into volume utils

Above function is only used in volumeops, so moved to volume_utils.
Also added some unit tests to cover that function.

Change-Id: I1298dd35d8a41832475c6d6bd908af8f6576be82
Enabled swap disk to be resized when resizing instance.

When you resize an instance, it is powered off and the root and
ephemeral disks are resized (not swap). Swap is not resized
because it is a partition. To allow the swap disk to be resized,
we have to delete it and re-create it with the correct size.
We do not care about the contents of the swap disk because
when an instance is shut down, the contents of the swap space
are just garbage, the OS doesn't bother about what is in it.

Change-Id: I2bb05f01af6c97e6860dcd79a68884101a13c7d4
Closes-Bug: #1244222
Block device API missing translations for exceptions

Added translations to exceptions raised in the API.

Change-Id: I7b8ba03b735297fee04011c90fc3c6e6f9e27a0e
Fixes typo error in Nova

This submission is to fix the typo error
in "nova/network/linux_net.py" file.

Change-Id: I7219503085eb17a8517ab12c3d9703007f2bc54e
Merge "Block device API missing translations for exceptions"
Merge "Fixes typo error in Nova"
Merge "xenapi: move find_vbd_by_number into volume utils"
Merge "Enabled swap disk to be resized when resizing instance."