Better error reporting for failed database setup

[abn]

Currently, if the database setup fails, the rule does not report the root cause. An example message would be as shown below. We probably need to improve this a bit.

[WARNING] Rule 0: com.redhat.victims.VictimsRule failed with message:
Could not create a VictimsSQL instance.

[seanf]

In addition, if victims-enforcer is configured not to fail the build in the case of metadata/fingerprint vulnerabilitiess, it probably shouldn't fail the build because of database problems either.