Users should be able to switch app context between their personal account, blogs, and posts, and any team / Organizations they're a part of.
As we add more complex features to the editor (such as T849) while maintaining a simplified UI, the software needs context to clearly distinguish between activities pertaining to a personal account or a team. (The org upload use case is described in T860.)
We've already implemented this UX on Snap.as, so we should do the same on Write.as.
Allow switching from the user dropdown menu on backend management pages.
TODO: more details