Work in Progress

hmm.. how would we get the `opts` parameter? I'm thinking something like
```
local test = require('luvit-tape').test('test_1', {highWaterMark = 128})
```

This would allow user to set `highWaterMark` for a `TestSuite`, but not the `TestSuites` stream. Shall we simply use a large number for `TestSuites` stream and document it somewhere?