roll the requests submodule back to kennethreitz/requests@99ebac7e8419c96020565d506cece8f6f3ac4c9e

when i updated it to
kennethreitz/requests@a44910b83760364ff5d679a567bacf5a4814caaa in
6eaaea94501b02dfa61508e49b217b89e1705b1f, i started seeing all https requests
infinite redirect and fail. not sure why; background in #58. rolling back
fixes it, so i'm just doing that for now.