Updated UI

Added a progress bar (indeterminate circle) centered over the roll
button. It is shown only during rolls.

Moved rolling to another thread

Roll Button is disabled during a roll

Change-Id: I6a6bfb9723af3b1292eb3df2f8810fb738f83876
Signed-off-by: Ricky Barrette <rickbarrette@gmail.com>

ExaltedDice/res/values/mod.xml

@@ -7,7 +7,7 @@
         <item>-3</item>
         <item>-2</item>
         <item>-1</item>
-        <item>0</item>
+        <item>+0</item>
         <item>+1</item>
         <item>+2</item>
         <item>+3</item>