packaging: use common structure that rhodecode-enterprise-ce is using for easier diffs

packaging: new wrapping logic on binary scripts: - don't additionally wrapp all scripts but only required ones

exceptions: use python3 compatible exception handling

scripts: drop broken, and not used vcsserver binary script

dependencies: bumped py.test to 3.8.2

dependencies: bumped hupper to 1.3.1

release: merge back stable branch into default

dependencies: dulwich, backported a patch to handle GIT references that are directories. - present in dulwich 0.19.X

patches: organize into a single directory.

dependencies: bumped GIT to 2.17.2 to address the security issues found in GIT