Android bitmap Face Cropper
##Usage
To crop faces automatically, you have to instantiate an object of FaceCropper class in that way:
FaceCropper mFaceCropper = new FaceCropper();
mFaceCropper.cropFace(source);
cropFace method supports int argument as a drawable resource, or directly a Bitmap.
##Configuration There are 4 important methods to configure its behavior:
setMaxFaces(int faces), to adjust the maximum number of faces to be recognized.
setFaceMinSize(int faceMinSize), in pixels.
setFaceMarginPx(int faceMarginPx), in pixels, and for each side.
setEyeDistanceFactorMargin(float eyeDistanceFactorMargin), as a multiplier of the distance between the detected face eyes.