Split reset_method into two separate methods

One that checks for redirects and one that actually resets
the stream.
Fix indentation pep8 issue
Reset the stream on retry

When we retry a request, we first need to rewind the stream
if possible.  Otherwise, we will only send a portion (or none)
of the stream which will cause the server to wait because our
content length won't match what we've sent.  Eventually the server
will just close out the connection.

Fixes aws/aws-cli#401.
Debug log the reasons we're trying a request

No functional change.
Fix type in comment
Merge branch 'cli-issue-401' into develop

* cli-issue-401:
  Fix type in comment
  Debug log the reasons we're trying a request
  Reset the stream on retry
  Fix indentation pep8 issue
  Split reset_method into two separate methods