Update for django==2.0

[jiunbae]

Django 2.0 released and there were some changes to the url function.

in hubblemon/urls.py(line 32)

...
    url(r'^admin/', include(admin.site.urls)),
...

It should be fixed as follows.

...
    url(r'^admin/', admin.site.urls),
...

And this is a pull request to fix it.

[jiunbae]

Or you can limit version of Django to less than 2.0. (If it is necessary)

[lynix94]

Thanks. I merge it.