Fix scene values type 'list' (Partially fix #266)

[robertsLando]

This is a partially fix of #266.

Please @ekarak check this commit. I have fixed list type values on scenes but there are still errors with 'decimal' types. The value is correctly stored in scene value (also in zwscene.xml) but when the scene is activate the value is not correctly parsed and it is set to default:

The value in zwscene.xml

<Value homeId="0xe84dc80d" nodeId="3" genre="user" commandClassId="67" instance="1" index="1" type="decimal">30.500000</Value>

When I call activateScene: zwave node 3: changed: 67:Heating:20.0 -> 5.0

It is set to 5 that is the min value.

This is the returned object value from getSceneValues

{ value_id: '3-67-1-1',
    node_id: 3,
    class_id: 67,
    type: 'decimal',
    genre: 'user',
    instance: 1,
    index: 1,
    label: 'Heating',
    units: 'C',
    help: '',
    read_only: false,
    write_only: false,
    min: 0,
    max: 0,
    is_polled: false,
    value: '30.500000' }

[ekarak]

thanks!