use mem and memsw failcnt, check for existence
info about cgroups on Debian, et al
Merge pull request #61 from ryanbcox/slurm-2.6

use mem and memsw failcnt, check for existence

Thanks Ryan.  I'll let you know how it goes.
Merge remote-tracking branch 'origin/slurm-2.6'

Conflicts:
	doc/man/man5/cgroup.conf.5
	src/plugins/task/cgroup/task_cgroup_memory.c