Improve and test server request line reading.
Improve and test server request line reading.

Shraddha512/rust-http,Shraddha512/rust-http,Shraddha512/rust-http,Shraddha512/rust-http,servo/rust-http,servo/rust-http,servo/rust-http,chris-morgan/rust-http,Shraddha512/rust-http,chris-morgan/rust-http,chris-morgan/rust-http,servo/rust-http,chris-morgan/rust-http