Only set a rails default locale when it's present

Setting I18n.enforce_available_locales = true would break apps not
setting a default locale via rails config

Fixes #417
Improve Persian Language, fa.yml
ru.yml has wrong permission, fixed that
Improve Persian Language, fix grammer problem fa.yml
add yotanami commit with some changes
Merge pull request #420 from Bersam/master

Update persian language YAML file
[fr] Fix login_as_existing translation

Fixes #423
upgrade i18n_data gem to 0.5.1

i18n_data gem 0.5.1 fix some translation of countries. Please use latest gem.

Fixes #422
[ru] add missing translations, improve consistency

Fixes #424
bump spree version
Dutch translation fixed (complete - voltooid)

Fixes #429
Only register before_filter set_user_language if it has not been registered yet, guaranteeing the filter retains its original position in the callback chain. Also, make sure the before_filter globalize_fallbacks is run before any other i18n filters.
Merge pull request #432 from jschwertfeger/fix/duplicate_set_user_language_filter_registration

Only register before_filter set_user_language if it has not been registe...
Fix missing interpolation "number" on translation to "order_number"
Add `number` interpolation for order_number in Thai
Merge pull request #435 from narze/patch-1

Add `number` interpolation for order_number in Thai
Merge pull request #434 from ddomingues/master

Fix missing interpolation "number" on translation to "order_number"
avoid buggy globalize 4.0.1, fixes #433

Conflicts:
	spec/models/product_spec.rb
	spree_i18n.gemspec

Conflicts:
	spree_i18n.gemspec
"Add translation to "shipment_details"
Merge pull request #437 from ddomingues/master

Add translation to "shipment_details"