justin: exit with failure if regexp does not match

This change will avoid an ugly stacktrace, but the issue is still present. The
"real" error message won't be drowned out though.
urplay: fix pylint warning (anomalous-backslash-in-string)
Add default handle method in Service base class

The default handle method will look for a supported_domains attribute
(a list), containing the supported domains. The subclassed service
class can of course override this if other means of determining support
is needded.
Rename Service's handle method to handles

handle can be ambiguous (i.e, not a verb).

Signed-off-by: Olof Johansson <olof@ethup.se>
Support supported_domains regexp for services

Lets services with more complex domains (like domains with language/country
codes) use a regular expressions that will match the supported domains for
the handles() method.