Proxy auto-entry prevents toggling votes

User can't toggle any votes before erasing the auto-entered proxy. This happened after upgrading the light client, and doesn't occur again after erasing the proxy field once. I couldn't reproduce even by upgrading the client on another machine.

**How to possibly reproduce**

1. Choose account with no proxy
2. Go to voting
3. Observe if proxy-field is populated
4. If it is, you shouldn't be able to toggle vote
5. When you clear the proxy field, you should be able to vote

Will post licecap when I successfully reproduce. First reported in TG by Pete Moss

Start at the voting screen with an account that has no proxy, and check whether the proxy field is auto-populated after the light client upgrade. Compare the vote-toggle behavior before and after clearing that field; done means the issue can be reproduced reliably and votes can be toggled without manually erasing an unintended proxy.

Written by the indexing model from the issue text.