[TIMOB-15746] Android : Blob which returned by toImage Method has undefined mimeType (parity issue)

Problem Description

Blob which returned by toImage Method has undefined mimeType in Android. In iOS is working fine.

Steps to reproduce

1. Create a new mobile project 2. Add support for android 3. Paste the code into app.js

var view = Ti.UI.createView({
    width : 100 ,
    height :100,
    backgroundColor:'blue'
});
var blob = view.toImage();
alert('blob.width:' + blob.width +
         '\n blob.height:' + blob.height +
         '\n blob.mimeType:' + blob.mimeType);

Expected Behavior:

{panel:title=Expected Alert Message} blob.width : 100 blob.height : 100 blob.mimeType : image/png {panel}

Actual Behavior:

iOS work properly, Buy Android alert below message {panel:title=Actual Alert Message} blob.width : 100 blob.height : 100 blob.mimeType : undefined {panel}