Options are required for announce

[okdistribute]

d.announce(key, opts) doesn't properly check to see if opts is empty before bailing.

/home/okdistribute/node_modules/workshop/node_modules/@hyperswarm/discovery/index.js:229
      localPort: opts.localPort || opts.port || 0,
                      ^

TypeError: Cannot read property 'localPort' of undefined
    at Discovery.announce (/home/okdistribute/node_modules/workshop/node_modules/@hyperswarm/discovery/index.js:229:23)
    at Object.<anonymous> (/home/okdistribute/node_modules/workshop/solutions/06/discovery.js:5:7)
    at Module._compile (internal/modules/cjs/loader.js:774:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:785:10)
    at Module.load (internal/modules/cjs/loader.js:641:32)
    at Function.Module._load (internal/modules/cjs/loader.js:556:12)
    at Function.Module.runMain (internal/modules/cjs/loader.js:837:10)
    at internal/main/run_main_module.js:17:11