Fix vagrant up error

[histrio]

Vagrant can't provision a machine

    default: + sudo docker run --link devel-backend:devel-backend --volumes-from devel-backend --name devel-webserver -d -p 80:80 brainless/devel-webserver:0.1
    default: cf5476c08fa6e84b674b913039111baef273c7e3bc14f4cf6da93fd139447eaa
    default: docker: Error response from daemon: Cannot link to a non running container: /devel-backend AS /devel-webserver/devel-backend.

It happens due to devel-backend container fail

IPython 6.0+ does not support Python 2.6, 2.7, 3.0, 3.1, or 3.2.

When using Python 2.7, please install IPython 5.x LTS Long Term Support version.

Beginning with IPython 6.0, Python 3.3 and above is required.

Quick fix is a ipython version restriction.

Signed-off-by: Rinat Sabitov rinat.sabitov@gmail.com