Add support for injecting how the Bitmap is drawn via Drawable inject…

…ion.

ion/src/com/koushikdutta/ion/BitmapDrawableFactory.java

@@ -0,0 +1,19 @@
+package com.koushikdutta.ion;
+
+import android.content.res.Resources;
+import android.graphics.Bitmap;
+import android.graphics.drawable.BitmapDrawable;
+import android.graphics.drawable.Drawable;
+
+/**
+ * Created by koush on 4/25/15.
+ */
+public interface BitmapDrawableFactory {
+    public BitmapDrawableFactory DEFAULT = new BitmapDrawableFactory() {
+        @Override
+        public Drawable fromBitmap(Resources resources, Bitmap bitmap) {
+            return new BitmapDrawable(resources, bitmap);
+        }
+    };
+    Drawable fromBitmap(Resources resources, Bitmap bitmap);
+}