chore(release): 2.0.0 [skip ci]

# [2.0.0](1.9.0...2.0.0) (2021-06-04)

### Code Refactoring

* **Defaults:** Export `defaults` object ([6b9b698](6b9b698))

### Features

* **Version 2:** Reduce package size ([cfcae8a](cfcae8a))

### BREAKING CHANGES

* **Version 2:** - Package now exports a `defaults` object
- Client.defaults has been removed
- All client config is now stored in `client.config`
- All resources have been removed from the client. Instead retrieve
these from the library and inject the client. E.g.
`client.postcodes.retrieve` becomes `postcodes.retrieve(client, ...)`
- Helper methods (like lookupPostcode, ping) have been removed from the client.
Instead retrieve these from teh library and inject the client. E.g.
`client.lookupPostcode` becomes `lookupPostcode(client, ...)`
* **Defaults:** Uppercased default variables no longer exported.
Instead `defaults` object is supplied

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@ideal-postcodes/core-interface",
-  "version": "1.9.0",
+  "version": "2.0.0",
   "description": "Interface specification for javascript based API Clients to api.ideal-postcodes.co.uk",
   "author": {
     "name": "Ideal Postcodes",