Added a Cors adapter and all tests now use that new adapter

Added a cors adapter and removed the cors and cookie auth support from
the http adapter. All test files can now simply add cors-1 to the list
of adapters to test against a cors config. Cors specific tests are in
test.cors.js. Fixed issue where http and cors dbs weren't getting
deleted after a test was complete. All browser and node-qunit tests
passing.