main blueprint splitted in:
- inventory
- networks

- Rename Host to Interface
- Create new Host table to group interfaces

Use the session instead of URL parameters to store the last network
chosen.

There is no point displaying the LDAP groups in the profile

- All created tokens are stored in the database.
  To revoke a token, we just delete it from the database.
  Tokens not found in the database are thus considered unvalid / revoked.

- Add button to copy generated token to the clipboard

- Redesign profile page

See https://clipboardjs.com

Open source icon set with ready-to-use fonts for bootstrap
See https://useiconic.com/open/

hosttags table required for the many-to-many relationship
See http://flask-sqlalchemy.pocoo.org/2.3/models/#many-to-many-relationships

- Several IPs (hosts) can be associated to one MAC address
- Host name shall be non nullable

- refactor Network class

pytest-factoryboy current version (1.3.1) is not compatible with
factory_boy >= 2.9
See https://github.com/pytest-dev/pytest-factoryboy/pull/54

- update conda image and all dependencies
- uwsgi now available in conda for Python 3.6 (no need to install gcc to
  install it via pip)
- add new dependency: factory_boy / pytest-factoryboy

Catch exception when no network exists (null is passed as network_id).

- network name should be unique and not nullable
- force all name fields to StringField

Don't ovveride SQLAlchemy __init__ method on db.Model classes.

See http://flask-sqlalchemy.pocoo.org/2.3/quickstart/:
SQLAlchemy adds an implicit constructor to all model classes which
accepts keyword arguments for all its columns and relationships. If you
decide to override the constructor for any reason, make sure to keep
accepting **kwargs and call the super constructor with those **kwargs to
preserve this behavior

ValidationError is catched by default by flask-admin.
It's easy to catch in the api/main.py to raise a CSEntryError.

We actually don't need to catch ValidationError as it's based on
ValueError that we already catch.

Use full exception error as message (error messages from psycopg2 can
be quite long but that makes it much more explicit)

TODO: we should maybe raise ValidationError in models
and catch that to raise CSEntryError in the API

Note that beginning with version 10, a major release is indicated by
increasing the first part of the version, e.g. 10 to 11.

So 10.1 will be a minor version. That's why we can use the docker tag
"10".

See https://www.postgresql.org/support/versioning/

The database constraints will catch the same error
(and raise an IntegrityError).

Having some validation at the model level allows to display nicer error
messages.
We use CSEntryError exception and not ValidationError so that it can be
used both by the API and views.

Allow to use the same CSEntryError exceptions used for validation
in the API and admin views.

Trying to insert an invalid IP or network address raises an exception.
This is due to the unique validator from flask-admin that queries the
database.

The unique validator is automatically added for columns with
unique=True. The only way to disable it is to monkey patch the Unique
class.
This allows the field validator to catch invalid format.

IntegrityError are already catched anyway.

- replace TextAreaField by StringField for several Text columns
- add filter to replace empty string by None on optional Text and INET
  fields

Don't override the Admin view __init__ method for consistency.
Avoid having to import models in admin/views.py

CIText is displayed as a TextAreaField by flask-admin.
Override it to use StringField.