Since PyCharm 2.7 you can hover over the inspected code and use the 
to Ignore errors like this.
Further more you can manage the ignored errors at Settings > Editor > Inspections > Python > PEP 8 naming convention violation > Ignored errors
Tested in PyCharm Community Edition 2016.3.2
Edit:
To remove the modification later on you can use 
to Show Only Modified Inspections and delete the Ignored errors with 
Tested in PyCharm Community Edition 2017.2.3