Install "node-legacy" for build
Install "node-legacy" for build

As can be seen in the build logs [1], this is failing with an error
about the "node" command, which on debuntu is provided by node-legacy.
Install it, as this seems to be the solution [2].

[1] http://logs.openstack.org/periodic/periodic-package-stackviz-element/5651097/console.html
[2] https://stackoverflow.com/questions/21168141/cannot-install-packages-using-node-package-manager-in-ubuntu

Change-Id: If4e6342182e978d1d8c09c21748dd3f150311afa

openstack/stackviz,openstack/stackviz,openstack/stackviz