Add options to ShallowWrapper#shallow

[ncuillery]

I have just enhanced the ShallowWrapper#shallow to support the same options arg as the top level shallow method.

It is useful when your component is wrapped by an high-order component like the ones provided in popular Flux implementations :

• http://fluxible.io/addons/connectToStores.html
• https://github.com/reactjs/react-redux/blob/master/docs/api.md#connectmapstatetoprops-mapdispatchtoprops-mergeprops-options

For example :

class MyComponent {
  [...]
}
MyComponent.contextTypes = {
  foo: React.PropTypes.string
}

export default connectToStore(MyComponent, [], () => {
  [...]
})

Then you can easily shallow render MyComponent:

const context = {foo: 'bar'};
const wrapper = shallow(MyComponent).shallow({ context })

I added the same context tests of shallow method to ShallowWrapper#shallow.

[lelandrichardson]

@ncuillery seems pretty reasonable. Looks like your branch is out of date though. You mind rebasing and fixing any conflicts?

Thanks.

[ncuillery]

Done !

[ncuillery]

Lint errors due to recent #276

I'll fix that