remove md_info, as node exporter supports it with v1.0.0-rc0

[judos]

The issue for the md_adm statistics can be considered closed with node exporter v1.0.0-rc0. See:
prometheus/node_exporter#261

We got now the relevant metrics. e.g.:

node_md_disks{device="md0",state="active"} 2
node_md_disks{device="md0",state="failed"} 0
node_md_disks{device="md0",state="spare"} 0
# HELP node_md_disks_required Total number of disks of device.
# TYPE node_md_disks_required gauge
node_md_disks_required{device="md0"} 2
# HELP node_md_state Indicates the state of md-device.
# TYPE node_md_state gauge
node_md_state{device="md0",state="active"} 1
node_md_state{device="md0",state="inactive"} 0
node_md_state{device="md0",state="recovering"} 0
node_md_state{device="md0",state="resync"} 0

Therefore we can remove the textfile scripts: md_info.sh and md_info_detailled.sh.

Cheers!