Sanitize inputs to strftime

Summary: strftime can read arbitrary memory. We sanitize the inputs before
calling strftime and throw an invalid arguement exception when they are out of
range.

Reviewed By: @JoelMarcey

Differential Revision: D1709836
Make newlines in http headers a fatal error.

Summary: Make newlines in http headers a fatal error.

Reviewed By: @markw65

Differential Revision: D1720703