Memoize global-id instead of creating objects every time.
Initialize activemodel-globalid in ActiveModel::Railtie
Merge pull request #5 from larrylv/memoize-global-id

Memoize global-id instead of creating objects every time.
Merge pull request #6 from yasuoza/initialize-in-railtie

Initialize activemodel-globalid in ActiveModel::Railtie
Supply more tests for SignedGlobalID
Merge pull request #7 from ifyouseewendy/master

Supply more tests for SignedGlobalID
Use the right instance of the application
ActiveRecord::Base is the subject inside on_load
Adds tests for the locate_signed method in
GlobalLocator that match the "locate" method tests.

Note that the invalid sgid test case currently raises a
ActiveSupport::MessageVerifier::InvalidSignature. I think the intended
design is for the initializer to return nil, but I wasn't sure.

SignedGlobalId initializer could check for a valid sgid.