pyros config files location

[asmodehn]

The files currently are created in /usr/var/pyros_setup-instance following flask configuration behavior.

It would be helpful to locate them in a more "intuitive" place, for someone who has a ros system already installed on the machine.

• /opt/ros/etc is one option.
• /etc/ros/pyros/ is another option.

I guess one or the other should be chosen depending on whether we should need to source /opt/ros/indigo/setup.sh before to be able to access it.

pyros-setup config file seems to fit the use-case for /etc/ros/pyros since it should be accessed and used implicitly, without sourcing anything (the whole point of it).
We probably need to modify pyros-config API in order to pass the location of the file to be created... pyros-dev/pyros-config#15