Code review comment for ~axino/charm-telegraf/+git/telegraf-charm:fix_unit_tests

A few lint failures (some unrelated to this change, but would be good to fix unit_tests/test_telegraf.py at least:

$ make lint
tox -e lint
lint create: /home/ubuntu/fix-unit-tests/.tox/lint
lint installdeps: flake8
lint installed: flake8==3.6.0,mccabe==0.6.1,pkg-resources==0.0.0,pycodestyle==2.4.0,pyflakes==2.0.0
lint runtests: PYTHONHASHSEED='1702027581'
lint runtests: commands[0] | flake8 reactive/ unit_tests/ tests/
reactive/telegraf.py:843:7: W605 invalid escape sequence '\d'
reactive/telegraf.py:846:7: W605 invalid escape sequence '\d'
reactive/telegraf.py:850:7: W605 invalid escape sequence '\d'
reactive/telegraf.py:854:7: W605 invalid escape sequence '\d'
reactive/telegraf.py:906:13: W504 line break after binary operator
unit_tests/test_telegraf.py:693:5: F841 local variable 'network_get' is assigned to but never used
unit_tests/test_telegraf.py:815:5: F841 local variable 'network_get' is assigned to but never used
ERROR: InvocationError: '/home/ubuntu/fix-unit-tests/.tox/lint/bin/flake8 reactive/ unit_tests/ tests/'
________________________________________________________________________________________________________________________________________ summary _________________________________________________________________________________________________________________________________________
ERROR: lint: commands failed
Makefile:19: recipe for target 'lint' failed
make: *** [lint] Error 1

Otherwise looks good.