* Clean up ref name rules

Clean up checks on reference names to better conform to the guideline
here: https://git-scm.com/docs/git-check-ref-format

This fixes half of #6321

* Update branch create integration test

According to: https://git-scm.com/docs/git-check-ref-format

And: git check-ref-format "master/feature=test1"

This is a valid branch name and we should not be testing for it to fail.

* Improve makefile + Add benchs

* Apply recommendations of @ethantkoenig

* Make URL scheme unambiguous

Redirect old routes to new routes

* Fix redirects to new URL scheme, and update template

* Fix branches/_new endpoints, and update integration test

* Create new branch from branch selection dropdown and rewrite it to VueJS

* Make updateLocalCopyToCommit as not exported

* Move branch name validation to model

* Fix possible race condition