Update props.py

Fix for "Text has no default property" in issue #118

modules/core/props.py

@@ -22,6 +22,7 @@ class Property(object):
             PropertyType.__init__(self)
             self.label = label
             self.configurable = configurable
+            self.default_value = default_value
             self.description = description
 
     class Actor(PropertyType):
@@ -64,4 +65,4 @@ class StepProperty(Property):
             PropertyType.__init__(self)
             self.label = label
             self.configurable = True
-            self.description = description
+            self.description = description