Address FindBugs issues and disable some detectors

This commit fixes enough FindBugs issues and disables enough detectors for `mvn findbugs:check` to pass.
I'm guessing the synchronization is meant to be there to prevent a race condition when two threads find `containsKey` to be false and try to invoke the put in https://github.com/andrewgaul/jclouds/blob/findbugs/apis/ec2/src/main/java/org/jclouds/ec2/compute/strategy/CreateKeyPairAndSecurityGroupsAsNeededAndReturnRunOptions.java#L160

I'm sure you saw that too, so unless I'm missing something it doesn't seem obvious to me why we should remove the synchronization.

Perhaps split that out into a separate PR where we can try to get in touch with the author and figure out what the intention was?

Any idea why FindBugs flags this up, by the way..?