SocketCreatorFactory does not null out instance static

The SocketCreatorFactory has a static "instance" field that keeps the singleton factory. The factory has a reference in "distributionConfig" that ends up keeping the InternalDistributedSystem alive after disconnect.
It also has a static close method but the product never calls it.
To fix this leak do the following:
On InternalDistributedSystem.disconnect add to the end of it:

          if (!attemptingToReconnect) {
            SocketCreatorFactory.close();
          }

Also I think it would be good to change SocketCreatorFactory.getInstance to null out the static when close it called like so:

  private static synchronized SocketCreatorFactory getInstance(boolean closing) {
    SocketCreatorFactory result = instance;
    if (result == null && !closing) {
      result = new SocketCreatorFactory();
      instance = result;
    } else if (result != null && closing) {
      instance = null;
    }
    return result;
  }