Use API version 1 instead of beta. Update docs

[mshamota-nr]

Version for Deamonset API is migrated according to
https://kubernetes.io/blog/2019/07/18/api-deprecations-in-1-16/
Without it, I wasn't able to run it locally.
I followed instructions in DEVELOPER.md and found that they need to be updated accordingly:)

[CLAassistant]

All committers have signed the CLA.

[bmcfeely]

Great! What will this mean for customers on older versions of k8s? Does someone in BCN know what our strategy should be for this? I think I saw that this issue exists somewhere else, but that someone didn't want to change yet. I don't know. :)

[Voziv]

Great! What will this mean for customers on older versions of k8s? Does someone in BCN know what our strategy should be for this? I think I saw that this issue exists somewhere else, but that someone didn't want to change yet. I don't know. :)

Ideally the chart should be versioned and stored in a chart repository. People who need the older api can still reference the older chart.

Would love to see this merged in soon as the chart doesn't currently work with our clusters