Create a BackPAN monitor

[preaction]

We need to make sure that BackPAN is being updated appropriately. The monitor should check to see if the indexes are older than 2 hours, and if so, send out an alert. The BackPAN indexes are:

$ ls -l /home/cpan/BACKPAN/*index.txt.gz
-rw-r--r-- 1 cpan cpan 11927534 Jan 16 19:22 /home/cpan/BACKPAN/backpan-full-index.txt.gz
-rw-r--r-- 1 cpan cpan  4289525 Jan 16 19:22 /home/cpan/BACKPAN/backpan-releases-by-age-index.txt.gz
-rw-r--r-- 1 cpan cpan  5420597 Jan 16 19:23 /home/cpan/BACKPAN/backpan-releases-by-author-index.txt.gz
-rw-r--r-- 1 cpan cpan  4328714 Jan 16 19:22 /home/cpan/BACKPAN/backpan-releases-by-dist-index.txt.gz
-rw-r--r-- 1 cpan cpan  4328720 Jan 16 19:22 /home/cpan/BACKPAN/backpan-releases-index.txt.gz