Implement voting system for Grandmaster Elections

[LeoVerto]

Is your feature request related to a problem? Please describe.
Right now grandmaster elections are handled using a reddit voting registration thread, a google form and a lot of manual work.

Describe the solution you'd like
We've got all the components we need for this already in squire: Authorization, data storage and the ability to do automated vote tallying.

This feature would require three additional tables:

• election: Stores metadata about elections.
• election_candidates: Pivot table for storing the candidates for each election.
• election_votes: Stores individual votes associated to the relevant election.

In theory we could also extend this feature to work for elections other than the Grandmaster one. For this to work, we'd need to be able to limit elections to certain ranks or battalions.