Url loads slider

[FRYoussef]

The url allows time parameters

[Akronix]

I found three issues:

• There are conflicts with the slider_controls branch that need to be solved. I tried a straightforward approach but it didn't work, so I reverted it. You need to address it with care.
• If you set the slider to the same point for both lower and upper bounds the app crashes with this error: KeyError: 'Attribute does not exist'
• An url with only upper_bound but not lower_bound has an error. For instance, this one: http://localhost:5000/app/?wikis=es.lagunanegra.wikia.com&network=co_editing_network&upper_bound=1274800435&lower_bound=1243696435 It gets this error:

  File "/home/akronix/workspace/wikis_research/WikiChron-networks/wikichron/dash/main.py", line 469, in update_slider
  low_val = (int(selection['lower_bound'][0]) - origin) // TIME_DIV
  KeyError: 'lower_bound'

  This kind of situations should be controlled. However, having only upper_bound seems to a robust behaviour, as expected.

[FRYoussef]

Done !!!

[Akronix]

It works great. Good job!