Comment 3 for bug 977362

I am surprised that /usr/local has lower priority than /usr, I've always thought that the convention is to use just the opposite order, but I guess that does not matter much, so it shouldn't be a problem.

Few important conclusions about proposed solution:
 - For each accomplishments set available we will need to remember it's path. That path would be used instead of accomplishments_path every time the API wants to access accomplishment's files.
 - We should assume these paths will not change while the daemon is running. Otherwise we would need rechecking their location every API call, which feels wrong, and consumes time&resources. This means the set's location detection may be done just once, when the daemon starts, and the paths would be remembered for later use.