Removed the special hack for 'Refinery Translator' role.

This adds complication to the core for a feature that could easily
be added by an extension when required.
Merge pull request #2730 from refinery/remove-translator-role

Removed the special hack for 'Refinery Translator' role.
Fixed bug: clicking Preview button causes Save button to open in a new browser window when clicked.
Instead of being configurable, made xhr_paging always enabled.

This option made no sense to be turned off because it makes for a better
user experience to prevent a full page reload when paging.