Bugfixes, new features, update to 0.2.0

- Current category available from com.holychao.parallel-test/*category*
  dynamic var.
- Current thread index available from com.holychao.parallel-test/*index*
  dynamic var.
- Obtain synchronization locks on *out* for all output operations.
- Fix bug where report was not invoked in failure or error.
- Monkeypatch around bug in clojure.test that causes inaccurate test
  statistics in summary report, when monkeypatching is enabled.
- Tighten thread local bindings of report counters to be reset and
  dereferenced per category.
- Fix bug around sorting namespaces when a category spanned multiple
  test namespaces.