Ref #1656: Update balance on claim grant after tokens are fetched

[kylehickinson]

This also fixes the bug where promos sometimes mess up when claiming them during publisher list load

Summary of Changes

This pull request references issue #1656

Submitter Checklist:

• Unit Tests are updated to cover new or changed functionality
• User-facing strings use NSLocalizableString()

Test Plan:

• Claim a grant
• Wait on panel
• Balance should update after 5s (if fetched tokens retry succeeds)

Reviewer Checklist:

• Issues include necessary QA labels:
  • QA/(Yes|No)
  • release-notes/(include|exclude)
  • bug / enhancement
• Necessary security reviews have taken place.
• Adequate unit test coverage exists to prevent regressions.
• Adequate test plan exists for QA to validate (if applicable).
• Issue is assigned to a milestone (should happen at merge time).