Fix variant thumbnails not showing on frontend

The thumbnails for variant would not show on variant click. And the
product page opened without any visible thumbnails.

Fixes #3130
When adding a variant to a RMA, do not mark the inventory unit as received until the RMA has been marked as received.

[Fixes #3121]
[Fixes #3180]
Remove create_inventory_units preference that is no longer used.
Namespace navigation tab translations so that they don't clash with translations such as en.spree.orders.show

Fixes #3133
Remove overridden deprecated methods and fix deprecation warning format thrown by them

Fixes #3055
Rename shipping_methods_zones table to spree_shipping_methods_zones

Fixes #3174
[api] StockMovements can never be altered (updated or destroyed), only created

Conflicts:
	api/app/controllers/spree/api/stock_movements_controller.rb
Correct habtm association for shipping_method zones

Related to #3174
Wait for API requests to finish in order_details_spec
Sleep inside orders/shipments_spec to also wait for an API response
[api] Skip set_expiry before_filter for states controller.

Ensure that swapping state input/select works in all contexts:

Set the default country to one without associated states so that
the spec verifies that if the selected country changes from without
associated states to one that does have them, we get the required
behaviour (the select is not hidden). Previously the spec only test
switching between two countries with associated states in teh db.

Fixes #3185
Revert "[api] Skip set_expiry before_filter for states controller."

This reverts commit 3f8b8076e96406af4050da5cc842a5c925dce8db.
[dash] account for situation where Jirafe is returning 503s
Add translation for 'currently_unavailable' to dash translations
Release 2.0.2
Bump versions to 2.0.3.beta
Remove spree_dash until Jirafe issues are resolved
Account for SocketErrors thrown by Spree::Dash::Jirafe.register

Fixes #3090
Fix documentation regarding in_taxon method

Fixes #3154
add `touch: true` option to Spree::Asset#viewable association

Fixes #3190