Add vnc_api method set_user_roles

This allows to manually set the roles of the user in the HTTP header.

Change-Id: Ifdf28ce18de55b3bed3e59de56de415da1839c2f
Partial-Bug: 1546057

src/api-lib/vnc_api.py

@@ -308,7 +308,7 @@ def __init__(self, username=None, password=None, tenant_name=None,
             if 'user' in self._user_info:
                 self._headers['X-API-USER'] = self._user_info['user']
             if 'role' in self._user_info:
-                self._headers['X-API-ROLE'] = self._user_info['role']
+                self.set_user_roles([self._user_info['role']])
 
         #self._http = HTTPClient(self._web_host, self._web_port,
         #                        network_timeout = 300)
@@ -1138,4 +1138,12 @@ def set_auth_token(self, token):
         self._headers['X-AUTH-TOKEN'] = token
     #end set_auth_token
 
+    def set_user_roles(self, roles):
+        """Park user roles for forwarding to API server for RBAC.
+
+        :param roles: list of roles
+        """
+        self._headers['X-API-ROLE'] = (',').join(roles)
+    #end set_user_roles
+
 #end class VncApi