fix default description to None.
NBI rejects an empty string as e.g. k8scluster, k8srepo

Change-Id: I99be7290c09ae1d76d0295a1a1c01b93cd28ae53
Signed-off-by: tierno <alfonso.tiernosepulveda@telefonica.com>
diff --git a/osmclient/scripts/osm.py b/osmclient/scripts/osm.py
index e3e2a28..43f37bd 100755
--- a/osmclient/scripts/osm.py
+++ b/osmclient/scripts/osm.py
@@ -2065,7 +2065,7 @@
               default='openstack',
               help='VIM type')
 @click.option('--description',
-              default='no description',
+              default=None,
               help='human readable description')
 @click.option('--sdn_controller', default=None, help='Name or id of the SDN controller associated to this VIM account')
 @click.option('--sdn_port_mapping', default=None, help="File describing the port mapping between compute nodes' ports and switch ports")
@@ -2266,7 +2266,7 @@
 @click.option('--wim_type',
               help='WIM type')
 @click.option('--description',
-              default='no description',
+              default=None,
               help='human readable description')
 @click.option('--wim_port_mapping', default=None,
               help="File describing the port mapping between DC edge (datacenters, switches, ports) and WAN edge "
@@ -2620,7 +2620,7 @@
               prompt=True,
               help='list of VIM networks, in JSON inline format, where the cluster is accessible via L3 routing, e.g. "{(k8s_net1:vim_network1) [,(k8s_net2:vim_network2) ...]}"')
 @click.option('--description',
-              default='',
+              default=None,
               help='human readable description')
 @click.option('--namespace',
               default='kube-system',
@@ -2794,7 +2794,7 @@
               prompt=True,
               help='type of repo (helm-chart for Helm Charts, juju-bundle for Juju Bundles)')
 @click.option('--description',
-              default='',
+              default=None,
               help='human readable description')
 #@click.option('--wait',
 #              is_flag=True,