Very little support for photosets

[LanaCoyote]

Most modern silos support photo posts with multiple pictures, but Redwind barely does. While the infrastructure is in place, you can't upload more than 1 picture to a post at a time, and our current silo plugins do not support POSSEing with more than 1 picture on a post.

Additionally, any contexts pulled from a silo post that has more than 1 picture only appears to retrieve the first picture in the post.

• [ ] Upload multiple pictures to a single post without saving it
• [ ] POSSE all pictures on a post (currently only POSSEs the first picture)
• [ ] Retrieve all pictures on a post in silo contexts (currently only retrieves the first picture)