add text, textSize, textColor attr support and subclass from ImageButton

[donpark]

I needed to build a PIN pad with circular buttons so added text support.

[Wolftein]

+1

[testkonto0]

Hi,
How to invoke manually SetText in my activity?

Edit:
Ok, I worked it out. If someone needed it must call:
CircleButton c = (CircleButton) rootView.findViewById(R.id.cc);
c.setText(params);