Expand the use of the reflected network check (See gh-1345)

As in 4d15d08e89358d1c99363e4b3bba4a7b690809ea, if the reflected check
can be used rely in it.  Furthermore, we will also now make use of the
java.net.InetAddress.isLoopbackAddress() method (available since Java
1.4) rather than looping through each and every possible interface and
retrospectively performing a string comparison on the actual addresses.
Add a testing main() to NetworkChecker