Call Recurly_Resource's constructor

PHP doesn't call parent constructors automagically, so if you override
it you need to call `parent::__construct()` yourself.
Each of the push notification types end with '_notification'. Updating comment to reflect that.
remove brackets in comment since this isn't a proper array anyway
Merge pull request #73 from richardkmiller/fix_push_notification_comment

Fix commenting in Recurly_PushNotification to match `type`
Update XML in fixtures
Add tests for parsing Adjusments
Test relations return Recurly_Stubs
Merge pull request #74 from recurly/update-fixtures

Update tests and fixtures
Add default coupon response
Updating the fixtures for current XML
Test coupon redemption
Test redeeming expired coupons
Error on non-redeemable coupons

Fixes #70.
Merge pull request #75 from recurly/coupon-redeem-tests

Coupon redemption tests
Version 2.2.4
Merge pull request #76 from recurly/bump-version

Version 2.2.4
Clearer use of applies_to_all_plans and plan_codes
Merge pull request #77 from recurly/more-coupon-testing

Clearer use of applies_to_all_plans and plan_codes
Merge pull request #67 from recurly/call-constructors

Call Recurly_Resource's constructor
readme; add support/announcements sections