References to `vi` API version replaced with `v1`

* Allow users to update their Account in the API

It would be nice for API clients to be able to allow users to update
their accounts without having to wrap Mastodon in a web view. This patch
adds an API endpoint to let users submit a PATCH for their account.

Signed-off-by: David Celis <me@davidcel.is>

* Add /api/v1/accounts/update_credentials to the API docs

Signed-off-by: David Celis <me@davidcel.is>

Redirect /:username to /users/:username
Redirect /:username/:id to /users/:username/updates/:id
Updated API documentation and sponsors

redis-backed "mentions" timeline as redundant (given notifications)

https://github.com/alin-rautoiu/mastodroid/issues/23