Google Code-in

See full task description here: https://phabricator.wikimedia.org/T207836.

Fix errors below;

./pywikibot/site.py:1789:17: W504 line break after binary operator
./pywikibot/site.py:2283:29: W504 line break after binary operator
./pywikibot/site.py:2286:25: W504 line break after binary operator
./pywikibot/site.py:2903:17: W504 line break after binary operator
./pywikibot/site.py:2904:17: W504 line break after binary operator
./pywikibot/site.py:3477:25: W504 line break after binary operator
./pywikibot/site.py:3478:26: W504 line break after binary operator
./pywikibot/site.py:4058:19: W504 line break after binary operator
./pywikibot/site.py:4059:19: W504 line break after binary operator
./pywikibot/site.py:4060:19: W504 line break after binary operator
./pywikibot/site.py:4061:19: W504 line break after binary operator
./pywikibot/site.py:4062:19: W504 line break after binary operator
./pywikibot/site.py:4063:19: W504 line break after binary operator
./pywikibot/site.py:4064:19: W504 line break after binary operator
./pywikibot/site.py:4065:19: W504 line break after binary operator
./pywikibot/site.py:4066:19: W504 line break after binary operator
./pywikibot/site.py:4987:40: W504 line break after binary operator
./pywikibot/site.py:6253:21: W504 line break after binary operator
./pywikibot/site.py:7581:61: W504 line break after binary operator
./pywikibot/site.py:7941:17: W504 line break after binary operator
./pywikibot/site.py:7942:17: W504 line break after binary operator