Remove forcebuild

[adiroiban]

As commented by @glyph

Since we've added the buildbot link to trac pages, force-builds.py is
basically obsolete.  I think we should  just scrub all mentions of it,
and probably delete it.

I can remove it and also take care of cleaning the wiki pages.

What do you think?

[glyph]

I guess it depends if anyone is using it or not. I don't see any way to figure that out though. Hopefully if someone is they will notice this issue and object.

[adiroiban]

OK. I have asked this on the list... will see if someone cares about this script.

[tomprince]

I haven't been actively working on twisted recently, but when I was, I used this script often.