Add a warning about the stability of Hyper to the README.
Exposed the 'from_one_raw_str' function for use in defining new header structs.
Merge pull request #83 from gtolle/expose-from-one-raw-str

Exposed the 'from_one_raw_str' function for use in defining new headers
Merge pull request #79 from reem/readme-warning

Add a warning about the stability of Hyper to the README.