bugfix: reset counter when pending points reached

otherwise this condition would be used no more than once and it would
only flush based on the timer.
camelCase variable names
networking/goroutine fixes

* break from TCP Accept() loop when connection closed, which was preventing shutdown to proceed
* make sure that UDP functionality doesn't write to writeSeries channel after it has been closed.
* clearer, more specific shutdown message

in particular:

 * self.writers allows us to make sure things writing to writeSeries are done
   (they do blocking calls to handleMessage()) whether udp or tcp
 * self.connClosed lets us break from the Accept() loop,
   see http://zhen.org/blog/graceful-shutdown-of-go-net-dot-listeners/ (quit channel)
 * shutdown channel is now allCommitted

things can get a little complicated, so here's a little schematic of how the functions and
their logic relate:
indent for a call out or important code within. everything shown as one nested tree

  server.go
      go ListenAndServe
          go committer
              reads from self.writeSeries until closed, then writes to self.allCommitted
          Serve
              for {
                  Accept, breaks if err + connClosed
                  self.writers.Add()
                  go handleClient
                      for {
                          handleMessage
                              reads until err and writes to self.writeSeries until read failed
                          reads until EOF, ignores other handleMessage errors
                      }
                      conn.Close()
                      self.writers.Done()
              }
              self.writers.Wait()
              close(self.writeSeries)
      Close()
          close(self.connClosed)
          self.conn.Close()
          wants confirmation on allCommitted channel; [timeout] returns within 5s