Add checks for if a file already exists before copying/creating in configure.py

[SteveMicroNova]

I've been doing stuff like this:

r'[ ! -d /var/log/journal ] && echo -e "[Journal]\nStorage=volatile\nRuntimeMaxUse=64M\nForwardToConsole=no\nForwardToWall=no\n" | sudo tee /etc/systemd/journald.conf',

In configure.py inside of my #828 branch, this checks if a file already exists and if not it can be created with default settings. This is useful for preserving user settings between updates and deploys, do this type of thing in all relevant places in configure.py to ensure that our systems support true user customization that isn't wiped out between updates.