Revert "icinga: remove check_ram.sh doesn't seem to be used anywhere"

This reverts commit 95fdd0550466d0e307504cdbdddc0c0709a8f60c.
check_ram.sh is used by Icinga on Wikimedia Labs.

Change-Id: Ieca1ef96e88a2b62b19019865646fbf63d1e666c
Merge "Revert "icinga: remove check_ram.sh doesn't seem to be used anywhere"" into production