Make tokens more accessible to assitive technologies

Summary:
Ref T4843.

  - The token award buttons are just icons.
  - The tokens themselves are just icons.
  - Also spread the tokens out a tiny bit, they feel a little tight to me right now.

Test Plan: Used VoiceOver to read out tokens and token actions. Looked at an object with several token awards.

Reviewers: chad, btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T4843

Differential Revision: https://secure.phabricator.com/D8982