ShellCheck: Static analysis for shell scripts

With the Icehouse release of Neutron impending, we’ve unfortunately uncovered a bug which is affecting ODL integration with Neutron. This bug was introduced by this commit, and the reality is better CI for the ODL plugin would have caught this. I’m going to work to enable this better CI in the near future. The workaround for this is to add the following in your nova.conf: I’m working on fixing this right now.