Require Twisted >= 8.2.
Require Twisted >= 8.2.

This is already required since [a1e1382d]
[2013-09-13T22:45:08Z!h.goebel@crazy-compilers.com], but I missed updating
the requirement then. According to
http://twistedmatrix.com/trac/browser/tags/releases/twisted-11.0.0/NEWS
single byte range is supported since Twisted 8.2.0. And that version of
Coherence only supported a single byte range.

furbrain/Coherence,coherence-project/Coherence,unintended/Cohen,furbrain/Coherence,ismaelgaudioso/Coherence,coherence-project/Coherence,ismaelgaudioso/Coherence,unintended/Cohen