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
Merge "Enabled swap disk to be resized when resizing instance."