Add lox distributor type with no allocated bridges

Let's add a new distributor type called "lox" that doesn't take any bridges but has it's own authentication token and will accept bridges that specify BridgeDistribution lox in their torrc file.

We'll need to do the following things

• Add a lox distributor to rdsys's config file
• Create a service for the lox distributor so it is restarted if rdsys-frontend-01 goes down
• Add the lox distributor binary to /srv/rdsys.torproject.org/bin on rdsys-frontend-01
• Add the lox distributor config file to /srv/rdsys.torproject.org/conf on rdsys-frontend-01
• Generate and add an API token for the lox distributor