Update site_config to use wildcard string for generic matching, rather than localhost

[BrianJKoopman]

When identifying the host and updating site.hub, site_config.get_config checks for the given site_host, the hostname of the computer, or 'localhost' in the site config file. Use of 'localhost' in the SCF should be discouraged.

This is done here:

ocs/ocs/site_config.py

Line 445 in 0709db2

host_attempts = [socket.gethostname(), 'localhost']

'localhost' should be replace with some unique wildcard string, i.e. '*default*', and a warning should be issued when it's used. The idea being that if you know the hostname, that should be configured in the SCF. Else, you're probably using this wildcard for some local testing on a single node.