Authorities reject relays running unsupported Tor release series.

Our minimum version is now 0.2.9.5-alpha.  Series 0.3.0, 0.3.1,
0.3.2, 0.3.3, and 0.3.4 are now rejected.

Also, extract this version-checking code into a new function, so we
can test it.

Closes ticket 31549.

Also reject 0.3.5.0 through 0.3.5.6-rc as unstable.