frontend: rename Pool to Type in vm popup widget

This small patch renames "Pool" label to "Type" in side tabs of vm popup
widget.

Change-Id: I94573205659f7411cf882ff23eeb73b343d4c39a
Bug-Url: https://bugzilla.redhat.com/1092379
Signed-off-by: Frantisek Kobzik <fkobzik@redhat.com>