Make eOS remember screen brightness

This is a common problem in Linux distributions, the only distro I have seen so far which does this is Linux Mint. Which means it is possible.

Elementary should remember the screen brightness as it was the previous session, and restore it the next.

One thing that popped to my mind, was that this may be an "issue" with X. In which case, one of the components of Elementary may issue a command to X telling it the previous screen brightness. The component should also save the state when shutting down the computer.