[Issue-70] Added Zoomable interface
[Issue-71] Added ImageViewZoomExtender class
[Issue-72] Added ZoomableNetworkImageView class
[Issue-63] Added PinchZoomNetworkImageView class
[Issue-73] Added MultiLevelZoomNetworkImageView class
[Issue-86] Removed unnecessary overloaded methods of panTo(..), zoomTo(..) in ZoomableNetworkImageView
[Issue-89] Added Restorable interface
[Issue-90] Added ZoomableComponent interface, and ZoomInfo POJO class
[Issue-91] Changed the super interface of ImageViewZoomExtender from Zoomable to ZoomableComponent
[Issue-92] Added Scaleable interface
[Issue-93] Changed the super interface of ZoomableNetworkImageView from Zoomable to ZoomableComponent
[Issue-94] Moved scaleTo(...) method from ImageViewZoomExtender to ZoomableNetworkImageView
[Issue-95] Applied Scalable into ZoomableNetworkImageView
[Issue-98] Removed initialize() and reset() in classes such as ZoomableNetworkImageView and ImageViewZoomExtender, and modified the classes to use restore() and save()
(NOTE: restore() and save() are not implemented yet until this commit.)
[Issue-83] Moved the role of setting a limit of levels from ImageViewZoomExtender to ZoomableNetworkImageView
[Issue-82] Removed getZoomExtender() from ZoomableNetworkImageView
[Issue-97] Changed a type of zoomExtender from ImageViewZoomExtender to ZoomableComponent in ZoomableNetworkImageView
[Issue-96] Implemented restore() method and save() which can restore a zoom level and a translate point after an device are rotated.
[Issue-99] Added isNewImageLoaded() into ZoomableNetworkImageView for detecting changes of a image
[Issue-108] Renamed MultiLevelZoomNIV to MultiLevelSingleTapZoomNIV, also PinchZoomNIV to TwoLevelDoubleTapZoomNIV