#149 Raw data storing format is added

[nadeyamalashevich]

Fix for the issue #149: Option to store/return raw value for dropdown.

[Hendy]

Hi @nadeyamalashevich Thanks for this PR :)
Yes, makes sense to pass the SaveFormat about rather than guess the type by the data 👍
I think the Raw option should only be available when it's a picker configured to select a single item (I know the TypeaheadList picker does something similar to restrict the CSV format)

[Hendy]

arh, guessing the save format from the data has the advantage of allowing the save format to be changed, and it'll still read in old saved data

[Hendy]

closing, as fixing #59 / #149 should resolve this