create separate options files for network plugins

remove plugin options from common files

inventory/sample/group_vars/k8s-cluster/k8s-net-flannel.yml

@@ -0,0 +1,16 @@
+# see roles/network_plugin/flannel/defaults/main.yml
+
+## interface that should be used for flannel operations
+## This is actually an inventory cluster-level item
+# flannel_interface:
+
+## Select interface that should be used for flannel operations by regexp on Name or IP
+## This is actually an inventory cluster-level item
+## example: select interface with ip from net 10.0.0.0/23
+## single quote and escape backslashes
+# flannel_interface_regexp: '10\\.0\\.[0-2]\\.\\d{1,3}'
+
+# You can choose what type of flannel backend to use: 'vxlan' or 'host-gw'
+# for experimental backend
+# please refer to flannel's docs : https://github.com/coreos/flannel/blob/master/README.md
+# flannel_backend_type: "vxlan"