Bump rails to 3.2.13
Fix delete link for taxonomies

since the Delete taxon url is look like this,
DELETE "/api/taxonomies/854451433/taxons558398399"
the delete process is not happening.
somebody missed a slash in between the 'taxon' and taxon_id

Fixes #2710
Mailers now require a from address, so we need to give defaults, using MailMethod.current

Conflicts:
	api/spec/controllers/spree/api/v1/shipments_controller_spec.rb
	core/app/models/spree/app_configuration.rb
tab are displayed only if user has :admin right on resource

Fixes #2626
should allow by default if cannot find associated resource (ex : overview)

Related to #2626
Truncate product description when used as meta description

Fixes #2396