Ability to allow all headers

[nsweeting]

It would be nice to allow all headers with something like:

plug Corsica, [allow_headers: :all]

[whatyouhide]

What's your use case?

[buhman]

I think related to #31, it makes sense to have an easily-visible option/default to add the simple headers (and content-type) from the spec.

I would hope I could just do plug Corsica, origins: "*" like it's suggested in the readme, and not have to read about allowed_headers and log and the entire preflight section of the cors spec just to understand why I'm not getting the behavior I want.

[whatyouhide]

Closed in 38b7d6d.