Merge branch 'simpler-shorthand' into develop

* simpler-shorthand:
  Add issue 484 to changelog
  Only document the simpler shorthand syntax
  Fix infinite loop in python3
  Pull up structure(scalar) bools into top level args
  Add more shorthand syntax support
Notify user when broken symlinks are encountered

You will now see an error message shown as well as a non zero
RC:

  $ aws s3 sync anotherdir/ s3://jamesls-test-sync/
  [Errno 2] No such file or directory: '/private/tmp/symlnk/anotherdir/z-badsylmink'

  $ echo $?
  1

There is potential to add something like a ``--skip-bad-symlinks``
option, but the default behavior is to let the user know that we've hit
a bad symlink.  Fies #425 and #487.