Branching process Julep

[simonbyrne]

We need to figure out how we're going to handle branching going forward. For the immediate future we plan to keep master as 1.1, but we will need to figure out how we want to handle breaking changes in the long term.

The key questions

• How to structure our branches?
• What tooling can we use to minimise the need for manual intervention with handling backports?
• What should get backported to minor and patch releases?

[oxinabox]

I think we should get rid of master, and just have 1.x-DEV and 2.x-DEV

Mechanical it is no different, but names matter