Shiftboiler

Minor bugfix release. Updated `User` model to change `flask_login` integration methods (`is_authenticated`, `is_active` and `is_anonymous`) from being methods to being properties to conform with [user mixins interfaces](https://flask-login.readthedocs.io/en/latest/_modules/flask_login/mixins.html#UserMixin).

Minor bugfix release that fixes issues with `setup.py` where a `python-dotenv` dependency is being used before it is acually available via `install_requires`, as described in [88](https://github.com/projectshift/shift-boiler/issues/88)

Further iterations of pagination improvements.

Bugfix release: fixing minor pagination issues on collections module and doing some extra regression tests.

Hotfix release to fix installation issues in `setup.py`

* Adds a pagination generation feature to navigation between pages, as per [36](https://github.com/projectshift/shift-boiler/issues/36)
* Fixes minor issue with IPython import in CLI when it doesn't exist which caused an exception to appear in stack traces.
* User service now notifies Principal when user logs in or out.