check warns wrongly about davfs use_locks

[ivh]

First off, thanks for box-linux-sync! I just found it and it seems to run nicely on Debian/Stretch.

A minor issue that I encountered: Running ./box-sync check triggered the warning

• Please set 'use_locks 0' in /etc/davfs2/davfs2.conf

for me, in spite of the option being set to 0 already in the config file.