Ignore node_modules
Make mongodb available
Add mongodb dependency
Add infrastructure to support multiple backends
CS fixes
Rename knock() -> group(), add new knock()
Restructure to support multiple backend caches
Merge remote-tracking branch 'origin/master' into add-mongodb-backend
Remove support for 0.6

Think this doesn't work on 0.6 because in 0.6, server.close() does not
take a callback. (Have to attach the close event separately?)
CS fixes
CS fixes
Add afirst()
Fix utils.js, simple.js
Disable cache, filter tests
Simplify

Remove function that's a bit too clever for its own good.
Fix test/cache.js
Fix test/filter.js
CS fixes
Support only-if-cached
Improve robustness of header handling