Update Phirehose so it doesn't choke on lower-case chunk headers

Upstream commit:
https://github.com/fennb/phirehose/commit/1558e1884a795aa2c52098ac45bf6e56ef0a765c
Merge pull request #17 from robinadr/phirehose-fix

Update Phirehose so it doesn't choke on lower-case chunk headers