Added A Roll Modifier Picker

Currently the roll modifier is from -5 to + 50. This can be updated via
values/mod.xml
Change-Id: I32c5d7ed1c67e0d8bc1b1434025d14134f8bc583
Signed-off-by: Ricky Barrette <rickbarrette@gmail.com>

ExaltedDice/res/layout/dice_selector.xml

@@ -13,6 +13,12 @@
     <NumberPicker
         android:id="@+id/d_Picker"
         android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_marginRight="20dip" />
+
+    <NumberPicker
+        android:id="@+id/mod_Picker"
+        android:layout_width="wrap_content"
         android:layout_height="wrap_content" />
 
 </LinearLayout>