Include BlindVote in API

[ab-10]

Blind Vote: All voting methods in analysis package, that use discriminativeQuery are referred to as blind vote, because they are blind to the definition roles.

The task is to provide them through the API, in a similar way that currently roleBasedVote is provided, however the methods should be called directly rather than duplicating the functionality in the handler (as it is being done for roleBasedVote).