Return LazyRenderer objects with view_cart

* It is required if downstream modules should be able to update the
  response context.
* Update dependency onf nereid 3.0.4.2 since the patch uses the
  capability in 3.0.4.2 to update headers in LazyRendered response
  objects
Merge pull request #26 from sharoonthomas/develop

Return LazyRenderer objects with view_cart