allow key combo clicking to select services during setup on FF browser

For the Connect demo, to reduce the number of clicks involved in setting up an Analytics node, please add a function to the setup wizard which will accept a Alt + click combo on one of the services checkboxes and which will subsequently select the clicked checkbox while de-selecting all other service checkboxes.

Till Westmann will figure out how/when/where the code is merged. So Pavel, please make the code magic happen, then re-assign this to Till.