jdg/MBProgressHUD — pull request #158 by lono175 (2013-08-22 15:00:15+00:00)
Title: - fix a possible memory leak

`cleanUp` set `self.indicator = nil` without remove `self.indicator` from the view hierarchy. It will introduce memory leaks if the MBProgressHud is reused several times with different indicators.
By removing `self.indicator = nil`, the indicator can be correctly removed from the view hierarchy when the MBProgressHud is assigned with a new indicator.