Merge branch 'master' into auth_fixes

* FEAT: Initial work on revision history for assets

The revision history for individual items mostly works, though it shows database ID where it should show asset ID. Recent changes feed isn't yet done.

* FEAT: Initial implementation of asset activity stream

* CHORE: Fix pep8

* FIX: Asset history table 'branding'

* FIX: Individual asset version history is now correctly filtered

* FEAT: Make revision history for suppliers accessible

* CHORE: *sings* And a pep8 in a broken tree...

* Refactored out duplicated code from `AssetVersionHistory

* CHORE: pep8

And another random bit of wierd whitespace I found

Co-authored-by: Matthew Smith <mattysmith22@googlemail.com>

Closes #358

RIGS/templates/RIGS/eventauthorisation_client_success.html

@@ -6,7 +6,7 @@
     <p>
         Your event <b>N{{ object.event.pk|stringformat:"05d" }}</b> has been successfully authorised
         for <b>&pound;{{ object.amount }}</b>
-        by <b>{{ object.name }}</b> as of <b>{{ object.last_edited_at }}</b>.
+        by <b>{{ object.name }}</b> as of <b>{{ object.event.last_edited_at }}</b>.
     </p>
 
     <p>

RIGS/templates/RIGS/eventauthorisation_client_success.txt

@@ -1,6 +1,6 @@
-Hi {{ to_name|default:"there" }},
+Hi {{ to_name|default_if_none:"there" }},
 
-Your event N{{object.event.pk|stringformat:"05d"}} has been successfully authorised for £{{object.amount}} by {{object.name}} as of {{object.last_edited_at}}.
+Your event N{{object.event.pk|stringformat:"05d"}} has been successfully authorised for £{{object.amount}} by {{object.name}} as of {{object.event.last_edited_at}}.
 
 {% if object.event.organisation and object.event.organisation.union_account %}{# internal #}
 Your event is now fully booked and payment will be processed by the finance department automatically.

RIGS/templates/RIGS/eventauthorisation_mic_success.txt

@@ -1,5 +1,5 @@
 Hi {{object.event.mic.get_full_name|default_if_none:"somebody"}},
 
-Just to let you know your event N{{object.event.pk|stringformat:"05d"}} has been successfully authorised for £{{object.amount}} by {{object.name}} as of {{object.last_edited_at}}.
+Just to let you know your event N{{object.event.pk|stringformat:"05d"}} has been successfully authorised for £{{object.amount}} by {{object.name}} as of {{object.event.last_edited_at}}.
 
 The TEC Rig Information Gathering System