Add event checkin functionality, seperate power tests into a different form (#536)

* Split power related parts of event checklist into a seperate form

* Revamp H&S overview, remove individual lists.

They were not a good thing.

* Remove old 'vehicle/crew' stuff

* Very initial version of checkin form

* Further work on checkin, add role field etc

* Fix tests after form split

* Add ability to edit checkins, more validation

* Basic checkin/out logic complete

* Add homepage checkin for events happening now

* Minor improvement to homepage UI

* Checkin button turns into checkout button where applicable

* UI work

* Clicking check out does not redirect the user

* Register check in model with the admin site

* Add power record status chip, checklist status chip displays number of checklists

* Minor fixes

* Implement codedoctor suggestions

* pep8

* Add data migration for crew/vehicles

* Checkin only requires login (no perms) and block users from editing other checkins at Django level

RIGS/templates/base_rigs.html

@@ -34,16 +34,7 @@
        </div>
     </li>
     {% if perms.RIGS.view_riskassessment %}
-    <li class="nav-item dropdown">
-      <a class="nav-link dropdown-toggle" href="#" id="navbarDropdownHS" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
-        H&S
-      </a>
-      <div class="dropdown-menu" aria-labelledby="navbarDropdownHS">
-        <a class="dropdown-item" href="{% url 'hs_list' %}"><span class="fas fa-eye"></span> Overview</a>
-        <a class="dropdown-item" href="{% url 'ra_list' %}"><span class="fas fa-file-medical"></span> Risk Assessments</a>
-        <a class="dropdown-item" href="{% url 'ec_list' %}"><span class="fas fa-tasks"></span> Event Checklists</a>
-      </div>
-    </li>
+    <li class="nav-item"><a class="nav-link" href="{% url 'hs_list' %}">H&S</a></li>
     {% endif %}
     {% if perms.RIGS.view_invoice %}
     <li class="nav-item dropdown">