Add propTypes definition to pass latest eslint-plugin-react

[Sheile]

The latest eslint-plugin-react (@7.13.0) notice following violations.

% npm run lint
  150:8   error  'dragDropManager.getMonitor' is missing in props validation  react/prop-types
  227:48  error  'dragDropManager.getMonitor' is missing in props validation  react/prop-types

✖ 2 problems (2 errors, 0 warnings)

Note

• 7.11.1 pass without violations
• 7.12.4 notice same violations

Reproduce

1. Clone repository
2. npm install
3. npm run lint

[coveralls]

Coverage remained the same at 75.579% when pulling 020e51c on Sheile:fix/eslint-violation into c87715a on frontend-collective:master.