Clarifying why test's load_conf() expects an exception

For a long while I've been puzzled why this load_conf() call asserted an
exception. When I ran it in a cusom prompt it ran fine - turned out that it was
relying on us having a custom DataDir. Tor balks (rightfully) when we'd shift
our DataDir out from a running tor instance.

Doing a better job explaining what's up in the comment.
Switching get_network_status() to provide v3 entries

Turns out 'GETINFO ns/*' provides v3 directory information rather than the v2
documented in the spec. Now that the spec is fixed swapping us over to take
advantage of it...

https://trac.torproject.org/7953
https://gitweb.torproject.org/torspec.git/commitdiff/d2b7ebb

RouterStatusEntryV3 provides a superset of the attributes of
RouterStatusEntryV2 so backward compatability shouldn't be a concern.
Adding Slackware to our download page

Markus just added stem to slackbuilds (hazaa!)...

http://slackbuilds.org/repository/14.0/python/stem/
Fix parsing of IPv6 address:port pairs in stream events (fixes #9181)