update to 2.2 branch

moved thumbnails to use deface to track better with spree_frontend

updated gemspec to work with master branch

tracking to 2-1-stable

fixed single quote typo

version bump

Update _image.html.erb

Update spree_product_zoom.gemspec

use asset_path to point to the zoom image for assets precompile

explicitly set the assets to include in precompile due to https://github.com/rails/rails/pull/7968

start zoom gallery on selected image, display variant images too