Add an install script and some minimal install instructions

This script gives us Nice Things like an upstart service and config file in /etc
install script: Delete existing files

This lets us avoid weird stale data from previous installs fucking with things
install: Add capability to run as user, and create it if needed

This allows the daemon to run correctly as an unpriveliged user,
without requiring any special setup from the administrator.
install: Add systemd support

Change the way you run it so that instead of running ./install directly,
you choose the relevant init system version and run that.
Add blank sample config for now

We can fill it in later, but it needs to exist as the installer wants to install it.
install: Be more selective about what we wipe when re-installing

We want to completely replace code directories (as opposed to a simple overwrite,
this won't cause problems when a file is no longer present or renamed).
We don't want to replace the config file.
We don't want to delete other stuff in the existing install dir, eg. auction logs.
We don't want to re-install dependencies unless we have to.
Rename the example config to make it more clearly only an example
Merge pull request #23 from ekimekim/installer

Add an install script