Add atom.syntax.grammars shim

src/syntax.coffee

@@ -28,6 +28,9 @@ class Syntax
     @subscribe @registry, 'grammar-updated', (grammar) =>
       @emit 'grammar-updated', grammar
 
+    #TODO Remove once packages have been updated
+    @__defineGetter__ 'grammars', -> @registry.grammars
+
     @nullGrammar = @registry.nullGrammar
     @scopedPropertiesIndex = 0
     @scopedProperties = []