Avoid deleting hack/bin/README when doing `make clean`

Reviewed By: @jwatzman

Differential Revision: D1672271

Signature: t1:1672271:1415731388:7cca4b1aaaba5eac37e9257ed7224db13dea2467
Add hh_server --version

Reviewed By: @jwatzman

Differential Revision: D1671853

Signature: t1:1671853:1415731292:b43c0e7e6c265bc51a276ca2a711f0e0fa8a3ab0
typechecker: ReflectionClass hhi fixup

Summary: ... implements Reflector was missing.

Reviewed By: @​mhabmajer

Differential Revision: D1672768

Signature: t1:1672768:1415732865:d233e4f3241c6bdaf11f10c4e896c3cf5f13e9ce