Hide 'Back' and 'Next' button if the number of step is 1
Hide 'Back' and 'Next' button if the number of step is 1

ng-modal has always buttons "Back" and "Next" even though
the number of step is one. In this case, we don't need to
show these buttons not to confuse users.

Change-Id: I5f2549f6add0c81263ee971d94fc24eb93e1e4ae
Closes-Bug: #1585065

coreycb/horizon,wolverineav/horizon,NeCTAR-RC/horizon,ChameleonCloud/horizon,bac/horizon,noironetworks/horizon,NeCTAR-RC/horizon,BiznetGIO/horizon,coreycb/horizon,coreycb/horizon,bac/horizon,bac/horizon,NeCTAR-RC/horizon,sandvine/horizon,ChameleonCloud/horizon,openstack/horizon,coreycb/horizon,BiznetGIO/horizon,noironetworks/horizon,BiznetGIO/horizon,ChameleonCloud/horizon,wolverineav/horizon,yeming233/horizon,bac/horizon,BiznetGIO/horizon,yeming233/horizon,wolverineav/horizon,openstack/horizon,openstack/horizon,NeCTAR-RC/horizon,openstack/horizon,noironetworks/horizon,ChameleonCloud/horizon,wolverineav/horizon,sandvine/horizon,yeming233/horizon,yeming233/horizon,noironetworks/horizon,sandvine/horizon,sandvine/horizon