Merge tag '1.5.1' into develop

Released v1.5.1.

Changelog available on the website.
Fix: make sure git hf update always returns to the right branch after an update
Setup tracking config correctly

.. to avoid 'git push' resulting in new remote branch called 'origin'
after 'git hf feature start my-fancy-branch-name-goes-here'
Merge pull request #48 from ymc-geha/feature/correct-remote-tracking-config

Setup tracking config correctly
Fix install instructions in README
Version bump
Merge branch 'release/1.5.2'