Correct registration of render functions

Register the render functions using a builder to ensure that they are
loaded by Plaid and before activating the views.
render: Use a context_processor
patches: unbreak single-patch view
Correct registration of render functions

Register the render functions using a builder to ensure that they are
loaded by Plaid and before activating the views.
Manage users with Flask-User

Switch to Flask-User for user and role management.  This also adds
password hashing.