fix type conversion of const bool

`prop: {const: True}` should be converted to bool and not to integer.

Change-Id: Ic3775a36c138d451dbad7615bc0e446528d8b0be
Signed-off-by: Artem Goncharov <artem.goncharov@gmail.com>

codegenerator/model.py

@@ -301,6 +301,9 @@ class JsonSchemaParser:
             if isinstance(const, str):
                 obj = ConstraintString(**schema)
                 return obj
+            if isinstance(const, bool):
+                obj = PrimitiveBoolean(**schema)
+                return obj
             if isinstance(const, int):
                 obj = ConstraintInteger(**schema)
                 return obj