* Bitmap is cleared only when setUri is called with empty/null uri
* update gradle & buildtools versions
* fix gradle plugin version
* rename assembleRelease to assemble task
* ImageView loads Bitmaps in Java so that they can be GC'ed.
Added ImageCache, AsyncLoading, Memory & DiskCache, Reusing Bimtaps
* Change FILE_PREFIX to match iOS file prefix.
* Refactoring package & class names
* Package renamed