uxl: add uxllauncher example + button example

examples/uxl/button.uxl

@@ -0,0 +1,21 @@
+#:uxl 1.0
+
+Widget:
+
+	Button:
+		label: "Hello World"
+		canvas:
+			Color:
+				rgb: (1, 0, 0)
+			Rectangle:
+				pos: self.pos
+
+
+	Button:
+		label: "I'm another label"
+		pos: (200, 200)
+		canvas:
+			Color:
+				rgb: (0, 1, 0)
+			Rectangle:
+				pos: self.pos

examples/uxl/uxlrun.py

@@ -0,0 +1,19 @@
+#!/usr/bin/env python
+
+from kivy.app import App
+from kivy.uxl import UxlBuilder
+
+class UxlApp(App):
+    def build(self):
+        uxl = UxlBuilder(filename=self.options['filename'])
+        return uxl.root
+
+if __name__ == '__main__':
+    import sys
+    import os
+
+    if len(sys.argv) < 2:
+        print 'Usage: %s filename.uxl' % os.path.basename(sys.argv[0])
+        sys.exit(1)
+
+    UxlApp(filename=sys.argv[1]).run()