Remove #noqa from two common imports and add them to import_exceptions

We have two imports with #noqa: django.conf.urls.patterns and
django.conf.urls.url however using them is a standard way of creating
any urls.py module. So there are over 150 imports in Horizon code
where #noqa could be replaced with two lines in list of import_exceptions.

Change-Id: I81c3290e0dc958b5037dd6a87e44df18adfbe751
Merge "Remove #noqa from two common imports and add them to import_exceptions"