Adjust bifrost node provisioning timeout and fix file permissions

Adjust bifrost node provisioning timeout and fix file permissions

This change
- increases the node provisioning timeout to 1900 seconds since the original
timeout used by upstream bifrost (900 seconds) is not suited for provisioning
VMs with Ubuntu.
- fixes permissions of the scripts.
- removes .gitkeep.

This change is not upstreamed since bifrost uses cirros for test & development
purposes and it is probably not in their interest to have increased timeout.

Change-Id: I4b59a321fa26f8b5895ec577a19d10f5cdcace0f
Signed-off-by: Fatih Degirmenci <fatih.degirmenci@ericsson.com>