[Fixes #31] Missing USPS First Class Mail
Typo Fix
Merge pull request #34 from jsqu99/usps_first_class_parcel_calculator

[Fixes #31] Missing USPS First Class Mail
Added support of weight limits for USPS & UPS and splitting order line items into separate packages when it exceeds the maximum weight.
Add Canada Post national & international services
Add specific error handling for Canada Post
Add french flag for Canada Post API
Decode HTML Entities in rate hash.

Handy for bilingual XML, Canada Post returns some fancy xml such as
"Postes Canada Colis acc&#xE9;l&#xE9;r&#xE9;s"
Fix for "Ready To Ship" in Canada Post API
Add locale to cache key
Allows Canada Post to recalculate values when the lang switches (service name and errors are localized)
Make sure we return nil when there's no package.
Will prevent CanadaPost from firing a request with no lineitem that will crash.
Fix for compatibility with 1.8.7 using iconv fallback
Merge pull request #43 from hooktstudios/canada-post-patch-2

Add support for Canada Post
Fix timing cache key naming
Cache responses errors (see spree/spree_active_shipping#38)
Otherwise the error is only shown on first user attempt
Rescue from shipping error in orders controllers.

Shipping price may be calculated when adding products to order if user is logged & address is filled.
Merge pull request #45 from hooktstudios/rescue-orders-patch

Rescue from shipping error in orders controllers.
Merge pull request #44 from hooktstudios/cache-fixes-3

Cache fixes 3
Added handling of case when variant weight is zero or negative value
Improved error handling, b/c exception.response can be instance of Net::HTTPServiceUnavailable also.
So, now we prevent errors like
NoMethodError: undefined method `params' for #<Net::HTTPServiceUnavailable:0xd5ba314>