Add authorisation process for sign ups and allow access to EventDetail for basic users (#399)

* CHANGE: First pass at opening up RIGS #233

Whilst it makes it something of a misnomer, the intent is to make the 'view_event' perm a permission to view event details like client/price. I don't see the point in giving everyone 'view_event' and adding a new 'view_event_detail'...Open to arguments the other way.

* CHANGE: New user signups now require admin approval

Given that I intend to reveal much more data to new users this seems necessary...

* CHORE: Fix CI

* FIX: Legacy Profiles are now auto-approved correctly

* Add testing of approval mechanism

This fixes the other functional tests failing because the user cannot login without being approved.

* Superusers bypass approval check

This should fix the remainder of the tests

* Prevent unapproved users logging in through embeds

Test suite doing its job...!

* FIX: Require login on events and event embeds again

Little too far to the open side there Arona... Whooooooops!

* FIX: Use has_oembed decorator for events

* FIX: Re-prevent basic seeing reversion

This is to prevent financials/client data leaking when changed. Hopefully can show them a filtered version in future.

* FIX: Remove mitigation for #264

Someone quietly fixed it, it appears

* FEAT: Add admin email notif when an account is activated and awaiting approval

No async or time-since shenanigans yet!

* FIX: Whoops, undo accidental whitespace change

* FEAT: Add a fifteen min cooldown between emails to admins

Probably not the right way to go about it...but it does work!

TODO: How to handle cooldown-emailing shared mailbox addresses?

* FIX: Remove event modal history deadlink for basic users

Also removes some links on the RIGS homepage that will deadlink for them

* FIX: Wrong perms syntax for history pages

* CHORE: Squash migrations

* FIX: Use a setting for cooldown

* FIX: Minor code improvements

RIGS/admin.py

@@ -22,13 +22,22 @@ admin.site.register(models.Invoice)
 admin.site.register(models.Payment)
 
 
+def approve_user(modeladmin, request, queryset):
+    queryset.update(is_approved=True)
+
+
+approve_user.short_description = "Approve selected users"
+
+
 @admin.register(models.Profile)
 class ProfileAdmin(UserAdmin):
+    # Don't know how to add 'is_approved' whilst preserving the default list...
+    list_filter = ('is_approved', 'is_active', 'is_staff', 'is_superuser', 'groups')
     fieldsets = (
         (None, {'fields': ('username', 'password')}),
         (_('Personal info'), {
             'fields': ('first_name', 'last_name', 'email', 'initials', 'phone')}),
-        (_('Permissions'), {'fields': ('is_active', 'is_staff', 'is_superuser',
+        (_('Permissions'), {'fields': ('is_approved', 'is_active', 'is_staff', 'is_superuser',
                                        'groups', 'user_permissions')}),
         (_('Important dates'), {
             'fields': ('last_login', 'date_joined')}),
@@ -41,6 +50,7 @@ class ProfileAdmin(UserAdmin):
     )
     form = forms.ProfileChangeForm
     add_form = forms.ProfileCreationForm
+    actions = [approve_user]
 
 
 class AssociateAdmin(VersionAdmin):