Update version to 3.1.1

The version in plugin.xml was no longer in sync with the version
in package.json.

plugin.xml

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?><plugin xmlns="http://www.phonegap.com/ns/plugins/1.0"
     xmlns:android="http://schemas.android.com/apk/res/android"
     id="phonegap-plugin-barcodescanner"
-    version="3.1.0">
+    version="3.1.1">
 
     <name>BarcodeScanner</name>
     <description>You can use the BarcodeScanner plugin to scan different types of barcodes (using the device's camera) and get the metadata encoded in them for processing within your application.</description>