Use urlutils functions instead of urllib/urllib2

urllib and urllib2 were reorganized in Python 3. This patch cleans up
code where use urllib/urllib2 directly. Also add unquote_plus to
py3kcompat urlutils.

See http://docs.pythonsprints.com/python3_porting/py-porting.html#url-related-modules

Implements: blueprint make-python3-compatible
Change-Id: If1c4a4d0f0dcfd98d4091e2adc5762933677eb67
Merge "Use urlutils functions instead of urllib/urllib2"