CB-7265: Fix crash in shouldOverrideUrlLoading on Android < 4.0.3

Application built with Cordova 3.5.1 running on a device with Android < 4.0.3 crashes when the webview is redirected to a custom url scheme. See https://issues.apache.org/jira/browse/CB-7265
More easily reproducible by adding the following line in JS: 
`window.location="custom://";`