[Fix] Mitigate XSS attack vector by cleaning input before it hits our Database (#171)

## Changes

- All text input fields are now cleaned with nh3 to remove html tags. We allow certain html tags under `settings.py/ALLOWED_HTML_TAGS` so we can easily update the tags we allow in the future.
- All names and descriptions now use the template tag `nh_safe` in all html files.
- Usernames and emails are a small exception and are not allowed any html tags

Co-authored-by: Liam Brydon <62733830+MyCreativityOutlet@users.noreply.github.com>
Co-authored-by: jebus <lorsbach@envipath.com>
Co-authored-by: Tim Lorsbach <tim@lorsba.ch>
Reviewed-on: enviPath/enviPy#171
Reviewed-by: jebus <lorsbach@envipath.com>
Co-authored-by: liambrydon <lbry121@aucklanduni.ac.nz>
Co-committed-by: liambrydon <lbry121@aucklanduni.ac.nz>

templates/migration_detail.html

@@ -27,7 +27,7 @@
                     {% endif %}
                     <h4 class="panel-title">
                         <a id="{{ obj.id }}-link" data-toggle="collapse" data-parent="#migration-detail"
-                           href="#{{ obj.id }}">{{ obj.name }}</a>
+                           href="#{{ obj.id }}">{{ obj.name|safe }}</a>
                     </h4>
                 </div>
                 <div id="{{ obj.id }}" class="panel-collapse collapse {% if not obj.status %}in{% endif %}">