step two: supply a ledger file argument to fullnode in the demo

(also whack unused "myip.sh", even though it was pretty)

multinode-demo/common.sh

@@ -107,9 +107,11 @@ tune_networking() {
   # Reference: https://medium.com/@CameronSparr/increase-os-udp-buffers-to-improve-performance-51d167bb1360
   [[ $(uname) = Linux ]] && (
     set -x
+    set +e # these error out on WSL
     # TODO: Check values and warn instead, it's a little rude to set them here.
     sudo sysctl -w net.core.rmem_max=26214400 1>/dev/null 2>/dev/null
     sudo sysctl -w net.core.rmem_default=26214400 1>/dev/null 2>/dev/null
+    :
   )
 }