* Use ascii decoding routine that disallows null chars
- GetAsciiString() in newer corefxlab builds allows 0 (which is a valid
ascii char). To avoid future regressions, GetAsciiStringNonNullCharacters()
was added and used in place of GetAsciiString() when interpreting the
request line and headers
- Make GetAsciiStringNonNullCharacters return empty instead of null
da763b4873
