log: route task/component status output through logging, not print()

AttributeChange (the common base of every ATask and component ABC) now
sets self.log = logging.getLogger(type(self).__name__), so components
no longer need to hand-type their own name into each message. Wired
logging.basicConfig() in server/brewpi.py with a bare "%(name)s:
%(message)s" formatter - Tee (see prior commit) still supplies the
"<date>T<time>:" prefix, so lines read "<date>T<time>:<component>:
<message>" without double-stamping, and third-party loggers
(websockets, asyncio) now get the same formatting for free.

Converted the print() call sites that were standing in for this in
tasks/ and components/ (leaving __main__ demo blocks and explicit
debug-dump helpers alone).

tasks/server_log.py

@@ -143,4 +143,4 @@ class ServerLogTask(ATask):
 		for name in (filename, self._latest_filename()):
 			with open(os.path.join(self.path, name), 'w') as f:
 				json.dump(log_data, f, indent='\t')
-		print('Server log: wrote {} samples to {}'.format(len(self._samples), filename))
+		self.log.info('Wrote {} samples to {}'.format(len(self._samples), filename))