fix: request proxy only after registering redis pubsub event listeners

[ThomasSelvig]

Previously, when requesting a proxy from a local redis instance it would sometimes not give a proxy but instead get the client stuck in the onProxyOffer client method. This would not happen with a remote redis instance, because there was a slight delay between asking redis for a proxy link and registering the event listeners.
Fix: move the "ask for a proxy link" call two lines down, so that the pubsub event listeners are registered before asking redis for a proxy link.