introduce real testing of the security manager with a sample policy file.

Initially we have one test passing (creating and cleaning up a temporary file),
and one test failing (altering a system property).
use semicolon when logging rules.

Format still needs work; classname should not have double quotes
and should not be followed by comma.
enable Checkstyle checks for test directory.

POM configuration was faulty before.
Reduced line length,
made methods final,
provided Javadoc,
replaced star imports