more logging options

[msfrank]

currently we only support logging to stdout, and is also an all-or-nothing approach (i.e. either everything gets logged or nothing does). we should add command line arguments for adjusting which levels of messages get output, which domains get output, and add support for logging to syslog or a logfile.

all of these changes should be relatively simple, the infrastructure is there (log levels and domains, twisted support for logging), they just need to be enabled and presented to the user in a reasonable way.

[msfrank]

related to this issue is implementing 'debug' mode, where logging goes straight to stdout (regardless of other configuration options) and the server does not daemonize. currently we do this by default, so we need to add the code for daemonizing and parsing the command line for a debug flag.

[msfrank]

logs should go to <environment>/logs/. logging should be configurable from the command line as follows:

-l,--logdomain DOMAIN: if specified, only log messages from DOMAIN; can be specified multiple times. If no log domain is specified, then messages from all domains are logged.
-v,--verbose: increase verbosity (up to -vvv)
-d,--debug: log to stdout instead of logfile; don't daemonize

[msfrank]

added logfile logging and proper --debug flag handling in changeset 490f67952bf1c4f427abfa1b18b296a711073774

[msfrank]

moving logging domain code to 0.2

[msfrank]

i'm gonna call this one good. the need for domain-filtering is just not pressing at the moment. maybe in a few releases i'll resurrect this ticket.