Creating a rack checks for wrong permissions

[jeremystretch]

Environment

• Python version: 3.6.8
• NetBox version: 2.7.3

Steps to Reproduce

1. Assign a user permission to create a rack (dcim.add_rack).
2. Log in as that user and attempt to create a rack at /dcim/racks/add/

Expected Behavior

The rack creation form should be displayed.

Observed Behavior

A 403 error (permission denied) is raised. This occurs because the URL configuration is actually pointing to RackEditView instead of RackCreateView, so Django is looking for the dcim.change_rack permission instead. (This permissions check is the only different between the two views.)