Add config option to change server port

[kmarius]

I wasn't sure if startUp should throw an exception if it fails. I just throw the last exception if none of the ports work.

[Adam-]

Any reason this is a list of ports and not just one port?

[kmarius]

I run several clients with the same config. This makes sure each of them gets a free port.

[Adam-]

Does that make sense? You wouldn't be able to tell which client got which port so why is that useful?

[kmarius]

I want to share the overwhelming majority of settings between my accounts, hence I only use one config. This way I can actually just switch accounts in OSRS without starting a new RL instance or logging to a different account. Right now I can only distinguish the accounts via API by their stats; I think it would make sense to expose the account name through the API.