uncap eventlet
uncap eventlet

We will manage the eventlet version using constraints now. See the
thread starting at
http://lists.openstack.org/pipermail/openstack-dev/2018-April/129096.html
for more details.

Change-Id: Ia15b42216c52e177d7fdf275ecb05b383c403a92
Signed-off-by: Doug Hellmann <0798ebecfb7bc4dfb9d0445c2fa030eb64e1fa1c@doughellmann.com>

openstack/tricircle,stackforge/tricircle,stackforge/tricircle,openstack/tricircle