Apply StrictNodes to hidden service directories early

Previously, we would sometimes decide in directory_get_from_hs_dir()
to connect to an excluded node, and then later in
directory_initiate_command_routerstatus_rend() notice that it was
excluded and strictnodes was set, and catch it as a stopgap.

Additionally, this patch preferentially tries to fetch from
non-excluded nodes even when StrictNodes is off.

Fix for bug #10722. Bugfix on 0.2.0.10-alpha (the v2 hidserv directory
system was introduced in e136f00ca). Reported by "mr-4".
Suppress warning in networks with only 1 dirauth.
Add changes file for ticket 10842.

This is a bugfix on 0.2.2.26-beta, because 6b83b3b made directory
authorities remove themselves from the list of directory authorities to
upload to, but didn't suppress the warning in case they're the only
directory authority in the network.
Merge remote-tracking branch 'public/bug10722'
Merge remote-tracking branch 'karsten/one-dirauth'