Move color processing to JS

Reviewed By: @vjeux

Differential Revision: D2346353

Examples/UIExplorer/BorderExample.js

@@ -26,12 +26,12 @@ var styles = StyleSheet.create({
   },
   border1: {
     borderWidth: 10,
-    borderColor: '#a52a2a',
+    borderColor: 'brown',
   },
   borderRadius: {
     borderWidth: 10,
     borderRadius: 10,
-    borderColor: '#00ffff',
+    borderColor: 'cyan',
   },
   border2: {
     borderWidth: 10,