test(header): test valid corner cases
test(header): test valid corner cases

Test corner cases that are easy to miss when coding such as equal sign
in the cookie value and empty and empty value.

hyperium/hyper,nickgonzales/hyper,hyperium/hyper,hyperium/hyper,tshepang/hyper,yazaddaruvala/hyper,tshepang/hyper,Twey/hyper,nickgonzales/hyper,Twey/hyper,nickgonzales/hyper,yazaddaruvala/hyper,tshepang/hyper,Twey/hyper