Image controls error handling

[BobDickinson]

The image controls (all platforms) take a "resource" parameter, which is a URL pointing to an image resource. If this fails in any way (badly formed URL, destination unreachable, download failed, etc), the client freaks out in a pretty spectacular way (spontaneous shutdown, generally).

Anyway, these all need to be reviewed and tested. The appropriate behavior is probably to just fail (eat the exception) and not show an image. Maybe log this somewhere?

Maybe we should have a backup/default image attribute (for when the supplied image fails), or maybe we should have some kind of "broken image" image that we show in this case.