Hide tabs for users without access.

Fixes #2860
Add shared admin examples.

Fixes #2856
Remove vtmb- class attribute from products/_thumbnails that isn't being used
Correct Taxons spec test for updating a taxon
Return html_safe strings from variant_price_diff

Fixes #2737
When using Russian Rubles, display the full currency symbol rather than just '.'

Fixes #2737
[backend] Remove link for shipments from orders/index list

Fixes #2876
[backend] Show 'This order has no payments' when no payments exist for an order
[cmd] Ensure there is a linebreak before gem lines inserted before installer

Fixes #2798
Allow the product description to go straight to the page raw.

Fixes #2874
Rename generate_api_key method in Admin::BaseController because it conflict's with spree_auth_devise's Admin::UsersController method of the same name