tests: Fix a duplicate test class name that doesn't match the filename.

This was the real cause of the redefined NAMESPACE constant, and could
cause other weird issues since setup will be overriden by one of the class
definitions.
Add IdentityCache.cache_namespace which can be a string or proc.
Merge pull request #91 from Shopify/cache-namespace-proc

Add IdentityCache.cache_namespace which can be a string or proc.
Relaxed activerecord and activesupport dependencies for rails 4
Update README.md
Update README.md
Merge pull request #96 from jdurand/master

Relaxed activerecord and activesupport dependencies for rails 4
Gemfile to use 3.2 for tests
Bump ar_transaction_changes to 0.0.3
Add require to AS attribute_accessors

ActiveSupport 4+ doesnt require that by default, so we need to include it.
Ignore all *.lock files
Merge pull request #99 from Shopify/attr_accesor_require

Add require to AS attribute_accessors
No need to tab the Class after creating it
Merge pull request #100 from Shopify/better_test_objects

No need to tap the Class after creating it
Make test record objects rails4 compatible
Update serialized fixtures
Merge pull request #101 from Shopify/scope_order_r4

Make test record objects rails4 compatible
Add ruby-head to travis
Add fast_finish to travis
add rails 4 gemfile