[JENKINS] important change in findbugs analysis

fyi, as part of the efforts to reduce bugs found by findbugs jenkins job, NORMAL priority bugs limit has been set to 15 (current count), this means that any NEW NORMAL bugs that will enter ovirt-engine code will fail the job, and it's the committer responsibility to fix it. if you're not sure about your code, you can run mvn findbugs:findbugs before merging (there's also an eclipse plugin for it). there is on-going work on reducing NORMAL bugs, and this limit will reduce in the near future, until it will reach '0' (similar to HIGH prirority). thanks for the cooperation. Eyal Edri oVirt infra team.