core,webadmin: Host reboot false for gluster only host

This patch sets requiresRebootAfterInstallation to false
in case of gluster only host.
Following UI flows for add host are changed
- Add New Host
- Reinstall Host
- Configure host (for Add Cluster)
- Import Cluster

Change-Id: I8c52e32de914b21998fa334088b302ec70aef49f
Signed-off-by: Sahina Bose <sabose@redhat.com>