Start aligning Parsoid cite with PHP cite behavior some more

* Nested ref tags are not supported anymore.

* Turned off pre and p-wrap handlers on ref content since the native
  cite extension seems to not do any of this on ref content.

* No change in parser test results (because there are no tests yet).

Other cleanup:

* Removed the 'inBlockToken' hack from Cite since this is not
  necessary anymore.

  TODO: The use of this flag in TemplateHandler may not be needed
  either. Verify and get rid of it.

* Leading whitespace in ref-content is still removed but this may
  not be strictly necessary.

Change-Id: I3406236032abe36099a1e420f443277a95fe597b
Merge "Start aligning Parsoid cite with PHP cite behavior some more"