Ability to add multiple terms from the same taxonomy to an item.

It is now possible to add multiple terms to an item in the same
taxonomy via the REST API. Terms not already present in the database
will be created.

Prefetch terms related to items when listing for performance

We got bad performance degrading as the number of terms increased.
Enabling django_debug_toolbar it was easy to see a bunch of queries
getting terms related to items duplicated as many times as items
in the system. Making the api view for listing items prefetch related
terms (and their taxonomies) removes these O(n) queries

Delete item from form

Added add item buttons.

Conflicts:
	django/website/hid/views/item.py

Add item frontend

The next hidden parameter in the form, which determines the redirect
following an update is set to the 'next' query parameter in the form.
If the query parameter does not exist, the HTTP_REFERER is used.
If neither exist, the user gets redirected to the dashboard.

Add the add item functionality. Also enforce a default value for item-type on forms. While the API allows for items without an item-type, the form's handling of it was inconsistant. Until we have a use case for items without an item type, a default is enforced.

Make the body text in the view&edit table link to the edit form.

Submit exceptions

Conflicts:
	django/website/hid/templates/hid/add_edit_item.html
	django/website/hid/tests/add_edit_item_view_tests.py
	django/website/hid/views/item.py

Conflicts:
	django/website/transport/items.py

Conflicts:
	django/website/hid/templates/hid/add_edit_item.html

Disable API URLs for security reasons

Timestamp formatting