SiriusConfig.getProp default to call by name

We don't need to evaluate the default value parameter until it's needed.
This saves a little work and headache, particularly with defaults like
SiriusConfiguration.HOST, where we're using
InetAddress.getLocalHost.getHostName (which is wonky at the best of
times).
Small cleanup of SiriusFactory

Pull out the common prefix in defense of typos. Add a little whitespace
to make it more clear what's going on.
Fix tty restoration logic in sirius-standalone

While this currently works the logic is off- we're checking to see
if saved_tty is empty, however saved_tty was never set. What we
meant to do was check if saved_stty is non-empty.

Additionally, move the exit portion out of the if as the if could be
not followed.
Merge pull request #63 from michajlo/fix-standalone-tty

Fix tty restoration logic in sirius-standalone
Merge pull request #66 from clinedome-work/getprop-default-by-name

SiriusConfig getProp default => call by name