Change logging to produce smaller logs by default (#7226)

Made access logging independent of facility logging.

Got rid of use of logger module for access logging.  It should be
independent of the logger module, because it should be independent
of the logging facility, and also shouldn't need anything more than
a write() call.
Added note to README about DPLA
Added logging of microseconds elapsed to access_log

The elapsed time is the time taken to get a result from the
service handler in multiprocess_http._wsgi_application(),
which basically amounts to the time taken to execute the code in
the module associated with the endpoint resource.