Remove zoom on double-click
Remove zoom on double-click

This was confusing in demos at KubeCon and DockerCon this year, as
clicking on nodes kept the UI zooming in.
Plus, when asked, users had no idea that double-click meant zoom in.

Fixes weaveworks/service-ui#453

alban/scope,kinvolk/scope,weaveworks/scope,alban/scope,alban/scope,weaveworks/scope,kinvolk/scope,alban/scope,kinvolk/scope,weaveworks/scope,kinvolk/scope,alban/scope,weaveworks/scope,weaveworks/scope,alban/scope,weaveworks/scope,kinvolk/scope,kinvolk/scope