title: Examples using CastCompanionLibrary to simply display an image
body: <p>I am looking for and example of casting an image to chromecast in android. Oddly enough it doesn't seem like this is covered in the googlecast sample repositories. Does anyone have a simple implementation of this? I basically would like to click on an image in my app's photo gallery on my android device and have it cast to the screen. 
  One side question is, does the image need to be at a url? or is it possible to stream the image to the device? I appreciate the help in advance.</p>