Be more careful with tracker handling.

  - When killing trackers, make sure the one we're killing is actually
    the same as the one we've been asked to kill.
  - Make sure we start the periodic timer when the startup timer fires.
Merge pull request #15 from brndnmtthws/master

Careful with tracker handling.
Add .gitignore.
Refactoring the code to make it easier to reason about
Use G1 GC.
Cleaned up imports.
Added meter for flaky tracker killing.
Increased JVM overhead.
Set -Xms in addition to -Xmx.
Fix for the tracker with no slots problem.
Metrics version bump, pom cleanup.
Switch G1 -> CMS.