Auto-install crontab; auto-update admin node's git repo

crontab.admin

@@ -2,7 +2,9 @@ MAILTO=compiler-explorer-admin@googlegroups.com
 PATH=/home/ubuntu/compiler-explorer-image/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
 
 # m h  dom mon dow   command
-00 00 * * * cronic /home/ubuntu/compiler-explorer-image/admin-daily-builds.sh
+00 00 * * * cronic bash -c "git -C /home/ubuntu/compiler-explorer-image pull"
+05 00 * * * cronic bash -c "crontab < /home/ubuntu/compiler-explorer-image/crontab.admin"
+10 00 * * * cronic /home/ubuntu/compiler-explorer-image/admin-daily-builds.sh
 00 03 * * * cronic bash -c "sudo /home/ubuntu/compiler-explorer-image/update_compilers/install_binaries.sh"
 05 03 * * * cronic bash -c "sudo /home/ubuntu/compiler-explorer-image/update_compilers/install_compilers.sh nightly"
 00 04 * * * cronic bash -c "sudo /home/ubuntu/compiler-explorer-image/update_compilers/install_libraries.sh nightly"