Add S.M.A.R.T metrics (#1209)
Add S.M.A.R.T metrics (#1209)

Update metrics following SMART attributes in [1][2]
- Seek_Error_Rate - ID: 7
- Reallocated_Event_Count - ID: 196

[1] https://en.wikipedia.org/wiki/S.M.A.R.T.#Known_ATA_S.M.A.R.T._attributes
[2] https://en.wikibooks.org/wiki/Minimizing_Hard_Disk_Drive_Failure_and_Data_Loss/Self-Monitoring,_Analysis,_and_Reporting_Technology

Signed-off-by: Dai, Dang Van <e0fc5ddd4a6ab8f2610f1e17e4c23f9fc438274c@gmail.com>
derekmarcotte/node_exporter,siavashs/node_exporter,siavashs/node_exporter,siavashs/node_exporter,derekmarcotte/node_exporter,prometheus/node_exporter,derekmarcotte/node_exporter,prometheus/node_exporter,siavashs/node_exporter,prometheus/node_exporter,derekmarcotte/node_exporter