Acquire Sauce Connect version on process run rather than import time,

to allow SAUCE_CONNECT_VERSION to be redefined from grunt-env.
Without this change the grunt-env settings would not have an effect.

I needed this because I wanted to run Sauce Connect 4.2 to check if it solves some tunnel problems. The package is currently fixed to 4.1. But it can be useful in general that one can set this variable from grunt-env, from the Gruntfile.js only.