Ability to configure fulldot/emptydot drawable

[bertrandmartel]

I've added the ability to set drawable id for FullDotDrawable & EmptyDotDrawable. Usage is for instance in CustomActivity` :

@Override
public int getFullDotDrawableId() {
    return R.drawable.pin_code_full_custom;
}

@Override
public int getEmptyDotDrawableId() {
    return R.drawable.pin_code_empty_custom;
}

Sample with rectangle shape with light_gray color :

Related #75

[Hatzen]

This looks fine to me. As i dont believe this will be merged so fast here is a (dirty) workaround for everyone interested:
Extend AppLockActivity and override onUserInteraction() to contain the following lines.

override fun onUserInteraction() { super.onUserInteraction() mPinCodeRoundView.setFullDotDrawable(R.drawable.pin_code_round_filled) mPinCodeRoundView.refresh(mPinCode.length) }

Big thanks @bertrandmartel