jQuery: continuing JSDoc

Introducing missing test suites / tightening up typings along the way.

This PR could prove controversial as part of it makes the simple ```text``` setter API compliant.  i.e. It goes from this:

```ts
text(textString: any): JQuery;
```

to this: 

```ts
text(textString: string): JQuery;
```
as per http://api.jquery.com/text/#text-textString

However, the jQuery documentation is littered with examples of passing numbers / booleans etc to ```text``` instead of strings.  Some examples:

- http://api.jquery.com/jquery.inArray/#example-0
- http://api.jquery.com/slideToggle/#example-1
- http://api.jquery.com/jquery.isFunction/#example-0
- http://api.jquery.com/mouseenter/#example-0
- http://api.jquery.com/mouseleave/#example-0

This makes me think that the examples in the jQuery documentation are wrong or that the jQuery API documentation is wrong.  I don't know which.

@dmethvin could you pitch in here perhaps?