Add button to return to main index

ics_id, serial_number, manufacturer_id and model_id should not change.
Repeating them in the history table takes space for nothing.

We are only interested in tracking the status, location and parent.

- catch IntegrityError on patch
- disable autoflush (IntegrityError was raised before commit due to
autoflush)

Pass ?qrcode=true as query string

Can use:

  -  /api/items?serial_number=123456
  -  /api/items?location_id=1

This allows a client to login only once a day.

We might want to decrease that and look into refresh token.
But this looks overkill for our use case.

- add more tests
- patching an item update children location and status
- setting the parent on an item updates the location and status with the
  parent ones

This can be done via the Admin interface but this latter shall be
restricted to admin users. This simple page allows the group "create"
to easily add new Manufacturer, Model or Location.

To make it easier, different decorators are created
depending if the user logged in using a JWT (API)
or cookie (web UI).

Clean code at te same time.
The macro from flask-bootstrap already takes care of everything.

- update flask-bootstrap
- update datatables to v1.10.15 for bootstrap 4 support

The CIText type is not known by Flask-Admin and was not rendered.
A custom model converter is required.

See https://github.com/flask-admin/flask-admin/issues/1196

The serial number might not be unique and can't be used
as the string to hash.
There are for example SD cards that all have the same SN.

Using an ICS id allows to pre-print labels that can be assigned to
hardware when scanning serial numbers.
This id shall be easy to remember (unlike UUID).

Most items won't have a name.
hostname could be added in a separate table if required.

User and Group shall not be created locally.
They all come from the LDAP/AD server.

Allow to easily pass config for testing

The citext module provides a case-insensitive character string type.
Use CIText for QRCodeMixin name column.
name should be case-insensitive to avoid duplicate names.

- We don't care about the id of the models. No need to force it.
- Rename actions