Fix route reference in shared/_alert so that it can be shared

Causes errors in custom admin sections otherwise.

Fixes #2564
orders api now returns its variants product id and description #2561
prefixed root_path with spree to make compatable with extensions

Fixes #2577
Fixes first order promotion rule

The previous logic applied to this rule prevented it from being eligible
in any context

Fixes #2569
Define group_by_products_id as a method so its existence isn't dependent on the table existing

Fixes #1247
[promo] Remove dependency on yaml fixtures
Just stub authorize! within testing_support/authorization_helpers
Only return unique ids from selected_taxons
Index shipments by order_id

Fixes #2594
count_on_hand setter no longer is accessible

Setting this attribute should be done through update_column instead, because otherwise this attribute is recalculated using recalculate_count_on_hand
Add closing tag for actions in admin/countries/index

Fixes #2615
now the taxons creation API works as documented

Fixes #2591
fix : ability params[:action] should be a symbol https://github.com/ryanb/cancan/wiki/Fetching-Records

Fixes #2609
not_deleted should include products 'deleted' in the future
Fix per item calculator to work when no promotion rules.

Fixes #2610
Check for presence of model_class before attempting to call it

Otherwise, this results in an undefined method error and has caused a segfault:

Exception `NilClass' at /path/to/spree/backend/app/controllers/spree/admin/base_controller.rb:19 -
undefined local variable or method `model_class' for
/path/to/spree/backend/app/controllers/spree/admin/base_controller.rb: [BUG] Segmentation fault
ruby 1.9.3p392 (2013-02-22 revision 39386) [x86_64-linux]

-- Control frame information -----------------------------------------------
c:0047 p:0026 s:0215 b:0215 l:000211 d:000214 BLOCK
c:0046 p:0012 s:0212 b:0212 l:000211 d:000211 METHOD /path/to/spree/backend/app/controllers/spree/admin/base_controller.rb:19
c:0045 p:0295 s:0208 b:0208 l:000207 d:000207 METHOD /path/to/.rvm/gems/ruby-1.9.3-p392/gems/activesupport-3.2.12/lib/active_support/callbacks.rb:462
c:0044 p:0115 s:0202 b:0202 l:000201 d:000201 METHOD /path/to/.rvm/gems/ruby-1.9.3-p392/gems/activesupport-3.2.12/lib/active_support/callbacks.rb:405
c:0043 p:0027 s:0193 b:0193 l:000192 d:000192 METHOD /path/to/.rvm/gems/ruby-1.9.3-p392/gems/activesupport-3.2.12/lib/active_support/callbacks.rb:385
c:0042 p:0024 s:0188 b:0188 l:000187 d:000187 METHOD /path/to/.rvm/gems/ruby-1.9.3-p392/gems/activesupport-3.2.12/lib/active_support/callbacks.rb:81
...
Freeze to i18n 0.6.1
[promo] Remove fixture usage
Bump to selenium-webdriver 2.30.0
Remove count_on_hand settings from products/edit/products_spec.rb

Setting this attribute "by hand" is no longer a valid way of doing it. You must
now use update_column. This attribute is not required to be set for these tests,
so removal is the best option.