NXDRIVE-524: Handle unset server_url and engine options
NXDRIVE-524: Handle unset server_url and engine options

rsoumyassdi/nuxeo-drive,arameshkumar/nuxeo-drive,arameshkumar/base-nuxeo-drive,arameshkumar/nuxeo-drive,arameshkumar/base-nuxeo-drive,rsoumyassdi/nuxeo-drive,arameshkumar/nuxeo-drive,ssdi-drive/nuxeo-drive,arameshkumar/base-nuxeo-drive,arameshkumar/base-nuxeo-drive,ssdi-drive/nuxeo-drive,arameshkumar/nuxeo-drive,rsoumyassdi/nuxeo-drive,rsoumyassdi/nuxeo-drive,ssdi-drive/nuxeo-drive