@JsonMiddleware doesn´t work with all_urls()

[exidio]

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• Bug
• Feature
• Question
• Documentation issue

If i want to use return state(__name__).routes.keys() I get the error message below.

Error Log

127.0.0.1 - - [22/Feb/2018 09:47:55] "GET /urls HTTP/1.1" 200 -
Error on request:
Traceback (most recent call last):
  File "C:\Users\i01002734\AppData\Local\Programs\Python\Python36\lib\site-packages\werkzeug\serving.py", line 270, in run_wsgi
    execute(self.server.app)
  File "C:\Users\i01002734\AppData\Local\Programs\Python\Python36\lib\site-packages\werkzeug\serving.py", line 261, in execute
    write(data)
  File "C:\Users\i01002734\AppData\Local\Programs\Python\Python36\lib\site-packages\werkzeug\serving.py", line 241, in write
    assert isinstance(data, bytes), 'applications must write bytes'
AssertionError: applications must write bytes

Expected behavior

It should give out all routes

How to reproduce the problem

Just use the return code above and call the route

Environment

OS: Windows 10
Swapy version: 0.2.1
Python version: 3.6.3

[Daniel Däschle]

dict.keys() returns a dict_keys object. Json is only str, list, dict, int and float (please forgive me if i forget one).
Commit 87c9a6f fixes this and inserts routes() function. Just use this instead with swapy.routes().