Don’t initialize index_view twice
Don’t initialize index_view twice

Since #1238 was merged, `index_view` would be initialized twice, which
caused the url of an `index_vew` passed in to `Admin.__init__()` not
being read (causing 404s for me 😢). This PR fixes that.
flask-admin/flask-admin,flask-admin/flask-admin,rochacbruno/flask-admin,flask-admin/flask-admin,flask-admin/flask-admin,rochacbruno/flask-admin,rochacbruno/flask-admin,rochacbruno/flask-admin