Refactor Unit Tests to test new sort ordering structure.

[avelis]

The following unit tests fail under the new feature #95
Will have to reteach the unit tests to assert the correct behavior. While this should have been done before it was merged into master. I am actively taking contributions in order to help resolve the growing list issues for this library.

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ERROR: test_default (tests.test_view_requests.TestContext)
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Traceback (most recent call last):
  File "django-silk/project/tests/test_view_requests.py", line 33, in test_default
    'order_by': RequestsView.defualt_order_by,
AttributeError: type object 'RequestsView' has no attribute 'defualt_order_by'

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ERROR: test_get (tests.test_view_requests.TestContext)
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Traceback (most recent call last):
  File "django-silk/project/tests/test_view_requests.py", line 50, in test_get
    context = RequestsView()._create_context(request)
  File "/Users/andrewvelis/Documents/django-silk/project/silk/views/requests.py", line 106, in _create_context
    filters=[BaseFilter.from_dict(x) for _, x in raw_filters.items()])
  File "/Users/andrewvelis/Documents/django-silk/project/silk/views/requests.py", line 70, in _get_objects
    raise RuntimeError('Unknown order_by: "%s"' % order_by)
RuntimeError: Unknown order_by: "Path"

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ERROR: test_time_spent_db_with_path (tests.test_view_requests.TestGetObjects)
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Traceback (most recent call last):
  File "django-silk/project/tests/test_view_requests.py", line 94, in test_time_spent_db_with_path
    path=request.path)
  File "/Users/andrewvelis/Documents/django-silk/project/silk/views/requests.py", line 70, in _get_objects
    raise RuntimeError('Unknown order_by: "%s"' % order_by)
RuntimeError: Unknown order_by: "Time on queries"

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ERROR: test_ordering (tests.test_view_requests.TestOrderingRequestView)
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Traceback (most recent call last):
  File "django-silk/project/tests/test_view_requests.py", line 111, in test_ordering
    self.assertSorted(objects=RequestsView()._get_objects(order_by='Recent'),
  File "django-silk/project/silk/views/requests.py", line 70, in _get_objects
    raise RuntimeError('Unknown order_by: "%s"' % order_by)
RuntimeError: Unknown order_by: "Recent"

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ERROR: test_order_by (tests.test_view_requests.TestRootViewDefaults)
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Traceback (most recent call last):
  File "django-silk/project/tests/test_view_requests.py", line 22, in test_order_by
    self.assertIn(RequestsView.defualt_order_by, RequestsView.order_by)
AttributeError: type object 'RequestsView' has no attribute 'defualt_order_by'

[avelis]

@trik This was my bad for not having better diligence in running the unit test suite before merging the pull request. I am looking in the near term to re-enable TravisCI to help everyone know when tests are failing.