Feature request: ScaleType as attribute so it can be set from xml

[bio007]

I would like to request simple handy feature to control scale type via xml attributes. Right now it can only be set from code calling setMinimumScaleType or (hacky) using databinding like this:

<com.davemorrissey.labs.subscaleview.SubsamplingScaleImageView
    android:id="@+id/photo"
    android:layout_width="match_parent"
    android:layout_height="0dp"
    app:minimumScaleType="@{2}"/>

Standard ImageView has this feature so it would be nice to have it here too.

Thank you!