Remove '-e' flag from docker login
Remove '-e' flag from docker login

This has apparently been dropped, and they decided that breaking
people was cool because they printed a warning for a while and who
uses docker in unattended workflows lol:

    https://github.com/moby/moby/issues/23390

So currently our deploys are broken:

    https://travis-ci.org/pypa/manylinux/builds/318363683

This should fix them.

Parsely/manylinux,manylinux/manylinux,pypa/manylinux,pypa/manylinux,Parsely/manylinux,pypa/manylinux,manylinux/manylinux