Description of problem:
If gdeploy is not installed on the system, running gluster deployment through cockpit wizard does not throw any valid error message and it just displays "deployment failed" which does not leave any clue to the user on what has happened.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. Install RHEL7.3
2. Install ovirt-cockpit-dashboard plugin.
3. Now launch the cockpit UI and start deployment.
cockpit Ui just displays and error "deployment failed" but does not give any error message on why it failed.
Display an proper error message on the cockpit UI on why the deployment has failed.
Tested with cockpit-ovirt-dashboard-0.10.7-0.0.15
'Hosted Engine with gluster' radio-button is disabled in the cases, when gdeploy is not installed