silence catting files that don't exist in docker entrypoint

Signed-off-by: Erik Hollensbe <git@hollensbe.org>

entrypoint.sh.release

@@ -1,7 +1,7 @@
 #!/bin/sh
 
 grepzt() {
-  [ -f /var/lib/zerotier-one/zerotier-one.pid -a -n "$(cat /var/lib/zerotier-one/zerotier-one.pid)" -a -d "/proc/$(cat /var/lib/zerotier-one/zerotier-one.pid)" ]
+  [ -f /var/lib/zerotier-one/zerotier-one.pid -a -n "$(cat /var/lib/zerotier-one/zerotier-one.pid 2>/dev/null)" -a -d "/proc/$(cat /var/lib/zerotier-one/zerotier-one.pid 2>/dev/null)" ]
   return $?
 }
 
@@ -34,7 +34,7 @@ mkztfile zerotier-one.port 0600 "9993"
 
 killzerotier() {
   echo "Killing zerotier"
-  kill $(cat /var/lib/zerotier-one/zerotier-one.pid)  
+  kill $(cat /var/lib/zerotier-one/zerotier-one.pid 2>/dev/null)
   exit 0
 }