Fail when the rundeck module was not loaded

Change-Id: Ic59325a4bc791b0934959b8af3f5cc1ed58ee788
diff --git a/_states/rundeck_project.py b/_states/rundeck_project.py
index 2e877a6..5919297 100644
--- a/_states/rundeck_project.py
+++ b/_states/rundeck_project.py
@@ -3,6 +3,16 @@
 LOG = logging.getLogger(__name__)
 
 
+def __virtual__():
+    if 'rundeck.get_project' not in __salt__:
+        return (
+            False,
+            'The rundeck_project state module cannot be loaded: rundeck is '
+            'unavailable',
+        )
+    return True
+
+
 def present(name, description=''):
     ret = {
         'name': name,