Feature: create new release command

[fzipi]

With the idea of automating most of the process for releasing, these steps from the release procedure might be easily automated:

Requirements

Example command: crs-toolchain release new -v v4.2.0.

This will:

1. Create branch for release. Call it release/$version
2. Update the copyright year and version in files
3. Git add/commit the files?
4. Create new PR with the branch? Add label +release
5. Create a new branch for post-release. Call it post-release/$next-minor-version"-dev".
6. Update the copyright year and version in files for the post release version
7. Git add/commit the files?
8. Create new PR with the branch? Add label +post-release