Start hacking on #148

I made a couple changes in the resource machinery and started in on
tests, and realized that this gets into the dispatch machinery.
Merge branch 'master' into spt
Prune set_trace call; #148
.spt implementation to fix #148
fix debug switch so it's on if ASPEN_DEBUG is defined
Merge branch 'master' into spt
Fix some .spt filename-based issues.
Get tests kind of passing for socket files; #148

These three tests in test_sockets_.py pass now, but one takes a few
seconds when I run that file in isolation, and hangs forever when I make
test. Wuh?!
Fix a couple more test cases for #148
Trim trailiing whitespace
Only init mimetypes if it isn't already; #148

See comment inline for more info. This is a workaround for a big test
slowdown that we're seeing between master and the spt branch. Need to
look into that.
Fix up the rest of the tests; #148

The tests are passing, though they're super slow. The only way they pass
at all for me is with that mimetypes.init conditional in the last
commit.
Merge branch 'master' into spt
Fix last socket test; #148

This test was originally breaking because we weren't properly starting a
socket thread because the filename was wrong and the content was wrong.
Now that the test is passing we needed to bring back the part where we
*close* the socket thread. That's where the slowdown was from. It's nice
though: the mimetypes.init thing still gives us almost a 4x boost in
test time. !m @pjz