Fix issue with request errors causing Node to terminate

Removed extra installation of error handler for HTTP request in putFile.
Removed wrappedFn so that putFile has the same callback behavior as
putStream.
Making these changes completely eliminated a problem I was having with
request errors being forwarded to the "progress" emitter returned from
putFile and causing Node to terminate.
See discussion here:
https://github.com/LearnBoost/knox/issues/207