Fix scope for admin tab translation. Spree backend navigation_helper.rb defines admin > tab as default
scope for translations.

Fixes #102
Ensure route is named as expected

This route is used as a named route in
app/views/spree/feedback_reviews/_form however it was not defined

This fixes that and fixes #101
Use the preview scope within shared/_reviews.html.erb

Change-Id: Ie319d29fb43a9cfb489dc34e48e263b6f7c97f07

Fixes #103

Conflicts:
	app/views/spree/shared/_reviews.html.erb
Merge remote-tracking branch 'upstream/2-1-stable' into 2-1-stable
translation [DE] Rezension > Bewertung
add bootstrap btn class