Changes:
* Add new MAX_MEMORY and TMPFS_LIMIT to allow limiting memory
* bulk: Show (-C) when used when deleting existing packages
* bulk: for install,deinstall,package,extract limit execution
time to 1 hour to avoid endless loops like devel/meta-cvs in
r337304
* Allow BUILDNAME to be overridden in poudriere.conf, such as:
BUILDNAME=$(TZ=UTC date +%Y%m%dT%H%M%SZ)
