automate new logging system

[zooko]

There is a nice new logging tool in foolscap 0.2.2 which we use in tahoe 0.7.0.

Unfortunately the way to use it currently requires a couple of manual steps:

1. pass FLOGTOOL=flog.pickle and FLOGTWISTED=1 environment variables to the tahoe process

2. find the resulting flog.pickle file (in your ~/.tahoe directory)

3. run flogtool dump flog.pickle on it to get a text output

3.b. alternately, run flogtool web-viewer flog.pickle on it to get a nice HTML view with indentation and coloration

We should probably spend some time trying to automate or at least document this process so that people who use tahoe v0.7.0 will have good logging.