Remove older services which are unlikely to work

[ryneeverett]

Once #791 is complete, the stakes of removing services that somebody might be using are less severe since there will be a well-supported way to run out-of-tree services.

For the next release, I think we should consider removing the following:

• ActiveCollab 2 & ActiveCollab4
  • This repository says it supports ActiveCollab 5 & 6 and it hasn't even been updated in 5 years. What are the odds that these services still work?
  • The person who contributed these -- and as far as I can tell the only one who ever interacted with an issue or pull request about them -- stopped using ActiveCollab about a decade ago.
  • The API docs seem to be entirely behind an authenticated login-wall, which is pretty bad even for proprietary services.
• Teamlab
  • The url redirects to Only Office.
  • It would be nice to support Only Office, but the api docs indicate it is on version 2.0 and our urls are on version 1.0.
  • As best I can tell nobody has interacted about this service since it was contributed over a decade ago.
  • It would probably be best that this service be re-contributed under the new Only Office name and the 2.0 api.
  • @umonkey -- any objection to removing Teamlab support?
• Version One
  • As best I can tell there has been no interaction with this service for over a decade.
  • The website seems broken.
  • @coddingtonbear -- any objections to removing VersionOne support?

[umonkey]

@ryneeverett no objections, ok to remove Teamlab.

[coddingtonbear]

Absolutely no objections considering that I haven't personally used bugwarrior in some time, and had totally forgotten that VersionOne ever existed (but probably could've guessed that trajectory from my memories of their app's quality).