Update OSFStorage w/ session management and requesting with session
Update OSFStorage w/ session management and requesting with session

This commit only changes the code where .make_request() is called by
replacing it with .make_request_with_session(). However, methods in
OSFStorage use both .signed_request() w/ context manager (CM) and
.make_signed_request() w/o CM interchangeably. Futher clean up is
recommended.

CenterForOpenScience/waterbutler,felliott/waterbutler