Adds a --show option to the image-create subcommand

Prints info about the new image when --show is used with the
image-create subcommand.

Change-Id: Id1fba67df9ff86cb1bbda3e241d1d03e01afbe2c
Closes-Bug: 1248128
Fix docstring on novaclient

Something like this:

1. Modify "`Image` to add metadata to" to ""`Image` to delete metadata" on
delete_meta()
2. Modify "The security group to delete" to "The security group to update"
on update()
3. Remove the "password" from the description on update()

Change-Id: I0120d84cc263d4eb58b692a5eb6f20ca0ef8264d
Closes-Bug: #1258461
Merge "Adds a --show option to the image-create subcommand"
Merge "Fix docstring on novaclient"