fix submitting on assignment with # in url

  added if statement to catch urls with lone #'s at the end when
  submitting assignments

  fixes CNVS-15812

  Test Plan:
  -Navigate to a published file upload assignment as a student.
  -Submit the assignment with a file.
  -Notice it succeeds.
  -Add a #<any text here> to the end of the assignment url so it should
  look like this: /assignments/:id/#<your text here> and refresh the
  the page until it actually reloads.
  -Submit the assignment again.
  -Notice it submits successfully
  -Navigate to /assignments/:id/# (make sure it actually reloads the page)
  -Submit the assignment.
  -The page should refresh and the Submit section of the page should have disappeared.
  

Change-Id: Ic81b4e7e51de96a20f7eae8c2fa609b82be6965a
Reviewed-on: https://gerrit.instructure.com/41756
Reviewed-by: Mike Nomitch <mnomitch@instructure.com>
QA-Review: Amber Taniuchi <amber@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
Product-Review: Simon Williams <simon@instructure.com>