Migrate library to kotlin, Update Libraries and Small Improvements

[BharathKSunil]

Changes:

• Incremented gradle version.
• Moving core library to kotlin
• Replaced calling invalidate immediately. Why?

protected void dispatchDraw(Canvas canvas) {
...
if (mIsRunning) {
                invalidate();
            }
}

with

override fun dispatchDraw(canvas: Canvas) {
...
if (isRunning) {
                ViewCompat.postInvalidateOnAnimation(this)
            }
}