you can choose where to put the menu controller (left or right)
Merge branch 'master' of https://github.com/kukat/NVSlideMenuController into kukat-master

Conflicts:
	NVSlideMenuControllerDemo/AppDelegate.m
	lib/NVSlideMenuController/NVSlideMenuController.h
	lib/NVSlideMenuController/NVSlideMenuController.m
Update implementation of sliding from right to left to open the menu.

* Rename `NVSlideMenuControllerStyle` into `NVSlideMenuControllerSlideDirection`
* Make a typed enum using NS_ENUM macro for `NVSlideMenuControllerSlideDirection`
* Rename `slideMenuControllerStyle` into `slideDirection`
* Fix menu view frame when sliding from right to left
* Fix bad appearance callbacks when sliding from right to left
Update demo to show the two directions.