Allow lists as smart_devices, fixes #15

[devster31]

The change is quite verbose, but should allow both lists and dicts as smartd_devices.
The list should have the following structure:

smartd_devices:
  - name: /dev/sda
    config:
      type: 3ware,1
  - name: /dev/sdb
    config:
      type: 3ware,2