CLI is not compatible with Python3

Since urllib library changes in Python3 the following error occurred while executing bagpipe-looking-glass bgp routes:

Traceback (most recent call last):
  File "/var/lib/openstack/lib/python3.6/site-packages/networking_bagpipe/bagpipe_bgp/cli/looking_glass.py", line 156, in main
    response = urllib.request.urlopen(target_url)
AttributeError: module 'urllib' has no attribute 'request'
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
  File "/var/lib/openstack/bin/bagpipe-looking-glass", line 8, in <module>
    sys.exit(main())
  File "/var/lib/openstack/lib/python3.6/site-packages/networking_bagpipe/bagpipe_bgp/cli/looking_glass.py", line 171, in main
    except urllib.error.HTTPError as e:
AttributeError: module 'urllib' has no attribute 'error'