Slice test runner script: Renew lease after setup

This branch updates slice test runner script so that it renews the board leases - since Gabriele recently found in some 3-board tests that the lease had expired by time that the capture transition was run. Error message:

     Error: [RuntimeError] Control app reported an error when running transition 'capture' (device 'serenity2.x0'): {
       "errorMessage" : "No application currently holds the lease",
       "errorType" : "LeaseExpired"
    }