The API/command rewrite in 0.5 regressed our log output, making it a bit

harder to gather useful debug information and to nicely show logging of

various levels.
Upon starting, we log a bunch of debug information, in order to help

with support requests. This matches what post-review used to show.
We now format different log levels in different ways.
Debug messages once again have a >>> prefix to help distinguish them

from other output.
Info messages are shown just like print statements, with no prefixes.
Warning and higher are in the form of LEVEL: message. This is a lot

nicer to look at when there's an error, since we now show

ERROR: <blah> instead of ERROR:root:<blah>.
The resulting logging looks like:
>>> This is debug
This is info
WARNING: This is warning
ERROR: This is error
CRITICAL: This is critical

Tested each logging level. Didn't see any duplicate messages.
Saw the useful new info at the top of the log output.
Tested without debugging and didn't see the debug output.