Updated default cron frequency

cron.txt

@@ -1,7 +1,7 @@
+0 */4 * * * python $HOME/misago/manage.py clearsessions
 0 3 * * * python $HOME/misago/manage.py clearalerts
 5 3 * * * python $HOME/misago/manage.py resetdeltas
 10 3 * * * python $HOME/misago/manage.py updateranking
 15 3 * * * python $HOME/misago/manage.py cleartracker
-20 3 * * * python $HOME/misago/manage.py clearsessions
-25 3 * * * python $HOME/misago/manage.py cleartokens
-30 3 * * * python $HOME/misago/manage.py updatethreadranking
+20 3 * * * python $HOME/misago/manage.py cleartokens
+25 3 * * * python $HOME/misago/manage.py updatethreadranking