Added Readme and updated config files with new config property - cssUrl.

src/styles/template.scss

@@ -5,6 +5,7 @@
  * Use BEM naming system for class names: http://getbem.com/naming/
  *
  * Use Mobile First approach.
+ *    Start with mobile device styling and then focus on other screen sizes by using @media (min-width: ...px).
  *
  */