Devel: set EDITOR to vi
Devel: set EDITOR to vi

At the moment, on the development container EDITOR is set to emacs, that
it's not installed at all.

I heavily use c^x + e to edit commands, and for me, having the EDITOR
variable set, it's a must.

Signed-off-by: Eloy Coto <2a8acc28452926ceac4d9db555411743254cf5f9@gmail.com>

3scale/docker-gateway,3scale/docker-gateway