"djadmin2theme_default" should not be hard-coded in templatetags.
Fixed ModelAdminBase2 to allow overriding existent views.
Added tests for pull-request #386

1. Custom views should be prepended to the 'views' list, otherwise they
   could be shadowed by views of the superclass.
2. Custom views should not be added to the superclass 'views' list.
   Instead a new list should be created and assigned to the class.
Merge branch 'patch-1' into develop
Merge branch 'patch-2' into develop