Add flexible usage options for CI jobs.

Added system property to overwrite pom.xml settings.
This should address concerns outlined in issue #18.

Usage example:
    mvn -Dvictims.skip.updates=true

Added 'weekly' updates option. Compares current date
and last update date to current year, and week of year.
This should address concerns outlined in issue #16.

Database synchronization issues will now not stop the
victims scan. If the synchronization operation fails we
print a warning message and try to continue the scan.
This should address the problem presented in issue #19.

All of these changes are experimental and require further testing.