Define site-updater touch file in update vars

To use Apache mod_wsgi, change $TOUCHFILE to point to the WSGI
file, and set "WSGIScriptReloading On" in the Apache config.

etc/update.vars

 MTNURL=127.0.0.1:8998
 MTNBRANCH=i2p.www.revamp
+TOUCHFILE=/tmp/2fcd2f17-c293-4f77-b4c9-9b266ba70daa

site-updater-i2hq.sh

@@ -15,5 +15,5 @@ fi
 
 if grep "^mtn: updating 'i2p2www/.*\.py\|^mtn: updating 'i2p2www/.*/.*\.py" "$TMP" >/dev/null ; then
   echo "Python files changed, restarting server"
-  touch /tmp/2fcd2f17-c293-4f77-b4c9-9b266ba70daa
+  touch $TOUCHFILE
 fi

site-updater.sh

@@ -15,5 +15,5 @@ fi
 
 if grep "^mtn: updating 'i2p2www/.*\.py\|^mtn: updating 'i2p2www/.*/.*\.py" "$TMP" >/dev/null ; then
   echo "Python files changed, restarting server"
-  touch /tmp/2fcd2f17-c293-4f77-b4c9-9b266ba70daa
+  touch $TOUCHFILE
 fi