In this patch we add the 'openstack share resize' command.
This command combines 'manila shrink' and 'manila extend' commands
into one and can be used to change the size of a share.
usage: openstack share resize <share> <new-size>
Change-Id: I052977f689ad4c1e9fb5f63d773519cd880c5b6c
Partially-implements: bp openstack-client-support