Simpler and more powerful decorator

See #48 for all the gory details.
To clarify, I'm on the fence about what I said in regards to changing the default. I'd be ok with both the "dangerous verbs" and "all" possibilities.

I do like the `ALL` thing.

We could introspect the decorated function/method name and use a different default when it's a "get" "post" etc. Would that make the API easier to use? Does it create worse edge cases?