Fix subdirectory deployments in a generic manner (#802)

* Fix subdirectory deployments in a generic manner by modifying`request.path` to combine both `request.script_root` and `request.path` and also creating a request preprocessor to redirect users into the true CTFd app. Without this sessions will be invalid because sessions will be set to a subdirectory. 
* Add a test for testing subdirectory deployments and the customized CTFdRequest object.
* Fix `TestingConfig.SAFE_MODE` getting stuck in between tests. 
* Order AWS keys properly in travis.yml
* Redirect to `request.full_path` instead of just `request.path`

tests/users/test_auth.py

@@ -116,7 +116,7 @@ def test_user_get_logout():
         client = login_as_user(app)
         client.get('/logout', follow_redirects=True)
         r = client.get('/challenges')
-        assert r.location == "http://localhost/login?next=%2Fchallenges"
+        assert r.location == "http://localhost/login?next=%2Fchallenges%3F"
         assert r.status_code == 302
     destroy_ctfd(app)