Scalable Platform/Username links in UserProfile

[zwaters]

At present, for every new plugin that is implemented an associated column in the UserProfile model must be added (e.g. for the facebook plugin, there's fb_id). This is obviously not scalable as we consider the sheer range of plugins that can be implemented for various online platforms.

[tommarmstrong]

@zwaters, I'm working on implementing this along with Wordpress plugin that I'm building. Basically I'm storing a platform identifier in a jsonb field in the UserProfile and then using that to match up posts to specific users