Fixes #132

The original code seems to check whether the type is really a
type constructor thus starting with an upper case letter.
The problem is that this check is done on the transformed name
of the type, which may no longer be an upper case letter
(e.g. when one uses camelTo2 '_'). Therefore, the check should
be done on the original name of the type, which then fixes
issue #132.

src/Data/Swagger/Internal/Schema.hs

@@ -680,11 +680,12 @@ genericNameSchema :: forall a d f proxy.
 genericNameSchema opts _ = NamedSchema (gdatatypeSchemaName opts (Proxy :: Proxy d))
 
 gdatatypeSchemaName :: forall proxy d. Datatype d => SchemaOptions -> proxy d -> Maybe T.Text
-gdatatypeSchemaName opts _ = case name of
+gdatatypeSchemaName opts _ = case orig of
   (c:_) | isAlpha c && isUpper c -> Just (T.pack name)
   _ -> Nothing
   where
-    name = datatypeNameModifier opts (datatypeName (Proxy3 :: Proxy3 d f a))
+    orig = datatypeName (Proxy3 :: Proxy3 d f a)
+    name = datatypeNameModifier opts orig
 
 -- | Lift a plain @'ParamSchema'@ into a model @'NamedSchema'@.
 paramSchemaToNamedSchema :: forall a d f proxy.