Is there anything that is built into the Buildfire platform that would easily allow a user from the "Widget" to upload and post photos to the Buildfire server?
I think you are looking for this API. https://github.com/BuildFire/sdk/wiki/File-System-Services
Then you want to pass your image to the get Server / CDN using https://github.com/BuildFire/sdk/wiki/How-to-use-ImageLib#buildfireimagelibcropimageurl-options-cdn-mode
Keep in mind usage is limited to your app tier