removed unreliable variable has_voted from voting template context
removed unreliable variable has_voted from voting template context

The item view was adding a variable has_voted to the voting template’s
context, but the vote action wasn’t — it wasn’t being used and
shouldn’t be, so I removed it; the variable vote should be tested
instead.

DemokratieInBewegung/abstimmungstool,DemokratieInBewegung/abstimmungstool,DemokratieInBewegung/abstimmungstool,DemokratieInBewegung/abstimmungstool