WIP: Default translations in app

[beausmith]

This is a WIP which does not fully implement the solution.

Problem

Election Manager should have the default strings it needs without requiring them to be in the election definition.

Solution

@eventualbuddha and I discussed that this may be better achieved with an update to the ballot-encoder method withLocale() where we update it to accept an additional defaultStrings param:

const spanishElection = withLocale(election, 'es-US', defaultStrings)

The withLocale fallback logic should be:

1. election definition: target locale value
2. app default: target locale value
3. election definition: primary locale value
4. app default: primary locale value

Status… want to discuss with @eventualbuddha to ensure this is the most solid solution.