Fixes shareViaSMS bug, opts.image present removes message body

[srhyne]

Issue...

If options.image passed, options.message was not present in iOS message controller.

• replaces getFile call with getImage call
• translates image to png and then attaches as addAttachmentData instead of addAttachmentURL

Modified:

• src/ios/SocialSharing.m

You can recreate the issue with the following code. "test" will not be added to the body of the SMS but the image will be present.

function testSharing(){
    var options = {
      message : 'test',
      image: 'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAUAAAAFCAYAAACNbyblAAAAHElEQVQI12P4//8/w38GIAXDIBKE0DHxgljNBAAO9TXL0Y4OHwAAAABJRU5ErkJggg=='
    }
  
    plugins.socialsharing.shareViaSMS(options)
}