Add hfsort to .gitignore.

Summary: Add hfsort to .gitignore.
Closes https://github.com/facebook/hhvm/pull/4146

Reviewed By: @sgolemon

Differential Revision: D1663371

Signature: t1:1663371:1415295773:22d534a602ab05709b93fb318e05087203b64dbf
http streams: only split headers into two pieces

Summary: Limit header explosions to two pieces to avoid truncating header data containing colons.
Closes https://github.com/facebook/hhvm/pull/4147

Reviewed By: @sgolemon

Differential Revision: D1663374

Signature: t1:1663374:1415295777:e15ae52ba0709f440ae0c8ae4ebece29884ff84a