header parsing to more closely follow rfc

[kevinkreiser]

so the vast majority of things making http requests out there seem to do so with header fields that conform to some rules: Caps-With-Dashes-For-The-Fields: a colon, a single space and then whatever for the value

Apparently, the fields are case insensitive and you can have any amount of white space between the colon and the value... So we should fix this... Specifically both ab and siege fail to properly POST because their content length header doesnt follow the rule above. Yuck!

@dgearhart