This PR provides support for editing embedded documents

Embedded documents is a key feature of the mongo database. It's also provided through mongoose.

This PR enables editing of embedded documents.

To use embedded documents, you need to create a mongoose schema and pass this into an Array property when creating a field, like so:

```js
staffMembers: [staffMemberSchema]
```

It's best not to include the schema definition in the same file as the model embedding it. Best practice is to create a folder called `schemas`, put it in there, and `module.exports` the schema itself. You can then `require` that schema in the model file.