Added allow-all (*) value to allowedOrigins and allowedHeaders. Normalised allowedMethods case

Thanks for this project! :)

First of all, just an fyi that there's a separate discussion in the NelmioCorsBundle to abstract away its functionality so that we could reuse it: https://github.com/nelmio/NelmioCorsBundle/issues/14

Until that gets fixed I wanted to have support for the * wildcard in origins and headers.

Let me know what you think