Manage users with Flask-User

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

The term "patch set" is much more common that "patch series" and in use
by other tools such as Gerrit.
Nicer navbar

A nicer looking navbar with breadcrumbs leading back to the project and
a user menu.
User profile editing

A simple form for editing a/the user's profile.
Global navbar

Use the navbar in every view and with appropriate breadcrumbs based on
the current context.
patch: Constrain patch headers width
breadcrumb: Remove spurious class

.breadcrumb is enough.
breadcrumb: Move it in a li element

Make the lint happier.
navbar: Rework the breadcrumb and remove the admin.css

Flask-admin currently isn't used and it was adding a 4px padding over
the bar.
registration: Overhaul form

Now it is following bootstrap3.
project: Add a description field
registration: Use breadcrumb instead of title
template: Do not use the page heading

The breadcrumb works better for navigation and highlight.
manage: Support setting the description
index: Prettify the start page
login: Update to bootstrap3

Use the standard placing and leverage the breadcrumb.
tags: Rework breadcrumb support

And drop the tags/ url.