Improvements to the JMX Checks

1. When the connection fails 3 times in a row, we won't try to open it up again.
2. The jmx process can be launched with a different priority (not by default)
3. I added an option in the jmx terminal to do a prefiltering of the values that are fetched which seems to add more stability to the jmx connector
4. Better failure handling
5. The check will only dump jmx domains that are actually used