Merge pull request #21 from jcsmesquita/master

Bring back missing patternReg.js and refactor all regular expressions…

lib/extract/patternReg.js

@@ -0,0 +1 @@
+export default /^url\(#(\w+?)\)$/;

lib/extract/patterns.js

@@ -1,6 +1,6 @@
 import rgba from '../rgba';
 let patterns = {};
-let patternReg = /^url\(#(\w+?)\)$/;
+import patternReg from './patternReg'
 
 import {LinearGradientGenerator} from '../../elements/LinearGradient';
 import {RadialGradientGenerator} from '../../elements/RadialGradient';