Add "Station mode" log output

[simonwo]

Station requires our logging to be in a specific output format.

A module communicates activity by writing to its stdout stream:

API: $1 The module has launched and $1 can be queried for fetching module stats (see below)
INFO: $1 $1 will be displayed to the user inside Station's Activity Log
ERROR: $1 $1 will be displayed to the user inside Station's Activity Log, with a warning icon
$1 all log lines will be stored in a module-specific log file, which can be submitted to Sentry for error handling

So the tasks are:

• In "Station mode", ensure log messages are printed to Stdout (and not Stderr)
• In "Station mode", ensure the log level (INFO, ERROR, DEBUG) is printed in all caps and full words at the start of the line
• In "Station mode", ensure the Station API endpoint (which may be the same as our normal Metrics endpoint) is printed to stdout as above.