Make it possible to install different versions of Spinnaker

[mafrosis]

It seems the current Spinnaker version is hard-coded:

https://github.com/afcastano/spinnaker-local-dev/blob/master/3-spinnaker.sh#L7
https://github.com/afcastano/spinnaker-local-dev/blob/master/3-spinnaker.sh#L31

[afcastano]

Hey @mafrosis , you are pointing to the version of the helm chart, not the spinnaker version itself. You can modify the spinnaker version here:
https://github.com/afcastano/spinnaker-local-dev/blob/master/values.yaml#L2

However, it would be a good idea to be able to modify the helm chart version.
I did harcode it in the first place because the newer version requires a k8s version that is not supported by gke yet, so it wasn't working when I deployed.

I'll add some settings for the helm chart and let you know.