Specify config file on commandline

[wraithan]

Would make dev on different bots at the same time easier. Services might need to inherit this behavior since they currently load ../bot.json

[wraithan]

Not backwards incompatible change, removing 2.x milestone.

[wraithan]

Needs docs, but exists.

[wraithan]

Still needs docs...

[wraithan]

Still needs docs...