Consolidate initialization of stats and logging from each main.go into cmd
package.
Define a new config parameter, `StdoutLevel`, that determines the maximum log
level that will be printed to stdout. It can be set to 6 to inhibit debug
messages, or 0 to print only emergency messages, or -1 to print no messages at
all.
Remove the existing config parameter `Tag`. Instead, choose the tag from the
basename of the currently running process. Previously all Boulder log messages
had the tag "boulder", but now they will be differentiated by process, like
"boulder-wfe".
Shorten the date format used in stdout logging, and add the current binary's
basename.
Consolidate setup function in audit-logger_test.go.
Note: Most CLI binaries now get their stats and logging from the parameters of
Action. However, a few of our binaries don't use our custom AppShell, and
instead use codegangsta/cli directly. For those binaries, we export the new
StatsAndLogging method from cmd.
Fixes https://github.com/letsencrypt/boulder/issues/852