Fix two issues in the chatkit image loader

First, I could reproduce #19 (closed) on the emulator again. The issue is that the recycler view switches the position of views and until the image is loaded again it stays in the wrong places. Directly removing the images fixes this.

The second issue is that individual profile pictures in group chat don't always have the same size and may not be square. This messes up our rendering in combineImages with these changes the app can handle images in any size and aspect ratio.