[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/modals/objects/edit_model_modal.html

@@ -1,3 +1,4 @@
+
 {% load static %}
 <!-- Edit Model -->
 <div id="edit_model_modal" class="modal" tabindex="-1">
@@ -16,12 +17,12 @@
                     <p>
                         <label for="model-name">Name</label>
                         <input id="model-name" type="text" class="form-control" name="model-name"
-                               value="{{ model.name }}">
+                               value="{{ model.name|safe }}">
                     </p>
                     <p>
                         <label for="model-description">Description</label>
                         <input id="model-description" type="text" class="form-control" name="model-description"
-                               value="{{ model.description }}">
+                               value="{{ model.description|safe }}">
                     </p>
                 </form>
             </div>