Add variant_id index to spree_prices

Necessary since we're spree_prices are automatically included when
listing products (whereever the default searcher is used)

Fixes #2612
We are switching to using TeamCity for our CI server
Remove restriction from Ruby 1.8
link to guest login for CI
[api] Ensure parameters are parsed correctly in VariantsController#create
Change out live() usage (removed in jQuery 1.9)

Fixes #2629
Error out when loading sample shipping methods if zones don't exist
Various small admin styles fixes
Remove duplicated use of select2() inside products/_form partial. Remove outdated comment on core gemspec. Fixes #2590

Fixes #2595

Fixes #2590
Change meta_description on spree_products from string to text

Fixes #2611
Adjust admin product tab selected

removing taxon from the list of controllers which make it selected

Fixes #2579
orders api now returns its variants product id #2561 #2565

Fixes #2587
Remove test restriction from around product_option_type_ids select2 setting in admin/products/_form
Display useful message when no payment methods, shipments (for orders) or shipping methods can be found

Fixes #2636

Conflicts:
	core/app/views/spree/admin/payment_methods/index.html.erb
	core/config/locales/en.yml
Insert non-breaking space in Money objects where currency symbol is afterwards to prevent issues as seen in #2634

This commit introduces the to_html helper for Spree::Money objects

Fixes #2634
fix: update_positions is not a rest action so it should not call load_resource

Fixes #2627
Fix percent per item calculator to work when no rules restricting products.

Fixes #2660
Fix issue with count_on_hand attribute in sample loading (#2631)
Update activemerchant to requiring at least 1.31.x

Fixes #2661
[sample] Add missing spec folder