devel/py-buildbot{-*}: Update to 1.5.0

All ports (where necessary):

• Fix and equalize *_DEPENDS (and specified versions) to setup.py.
• Match COMMENT to setup.py:description.
• Add commented LICENSE_FILE describing why its not defined.

py-buildbot{-worker}:

• Enable concurrent (Multiple Python version) installation.
• Update test targets to set PYTHONPATH, so that the package in WRKSRC. is tested, not installed packages.

py-buildbot:

• Remove post-patch target, no longer necessary.
• Add test dependency not declared in setup.py:test_requires, that cause tests to fail when not installed, unlike other dependencies that are skipped.
• Add an un-referenced compulsory RUN_DEPENDS on pyyaml reported and resolved upstream [1].

py-buildbot-worker:

• Update patch-setup.py to actually fix (package/install) the VERSION file, rather than just not installing it. The worker passes this files contents to the master for display in the frontend if it exists, otherwise sending the string 'latest' or the modification datestamp of another file. [1]
• Fix startup script to use the filename of itself (the executed script), not a filename that uses the ${name} variable, which doesnt exist as it contains an underscore (not a dash), causing the following error when executed:
  
  /usr/local/etc/rc.d/buildbot-worker: /usr/local/etc/rc.d/buildbot_worker: not found

Changelog:

http://docs.buildbot.net/current/relnotes/index.html#buildbot-1-5-0-2018-10-09

[1] https://github.com/buildbot/buildbot/pull/4394

Requested by: Tao Zhou <tao ish com au>
Reviewed_by: Nathan Owens <ndowens yahoo com>, 0mp
Differential Revision: D17821