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).

utils/value.py

@@ -1,3 +1,4 @@
+import logging
 
 
 class Value:
@@ -53,6 +54,12 @@ class ChangedInteger(object):
 class AttributeChange(object):
 	def __init__(self):
 		self.callbacks = {}
+		# Common ancestor of every task (tasks/task.py's ATask) and component
+		# (Connectable/APid/APlant/ATemperatureSensor) - giving it a logger
+		# here makes self.log available everywhere via one change, named
+		# after the concrete subclass so log lines self-identify their
+		# component without each call site typing it out.
+		self.log = logging.getLogger(type(self).__name__)
 
 	def set_on_changed(self, key, on_changed):
 		if key not in self.callbacks: