Basic example fails due to babel configuration

We've been maintaining a project based on `basic-starter-api-gateway-v1` for about a month now with no issues. We tried to issue an update today and started running into babel configuration errors. I went back to a fresh copy of the standard example out of this repo and I get the same error when running `npm run setup`. It seems to happen in the packaging process.

```
ReferenceError: Unknown plugin "transform-runtime" specified in "/Users/tylerfisher/src/serverless-express/examples/basic-starter-api-gateway-v1/node_modules/regenerator-transform/package.json" at 0, attempted to resolve relative to "/Users/tylerfisher/src/serverless-express/examples/basic-starter-api-gateway-v1/node_modules/regenerator-transform" (While processing preset: "/Users/tylerfisher/src/serverless-express/examples/basic-starter-api-gateway-v1/node_modules/babel-preset-es2015/lib/index.js")
at /Users/tylerfisher/src/serverless-express/examples/basic-starter-api-gateway-v1/node_modules/babel-core/lib/transformation/file/options/option-manager.js:180:17
at Array.map ()
at Function.normalisePlugins (/Users/tylerfisher/src/serverless-express/examples/basic-starter-api-gateway-v1/node_modules/babel-core/lib/transformation/file/options/option-manager.js:158:20)
at OptionManager.mergeOptions (/Users/tylerfisher/src/serverless-express/examples/basic-starter-api-gateway-v1/node_modules/babel-core/lib/transformation/file/options/option-manager.js:234:36)
at OptionManager.init (/Users/tylerfisher/src/serverless-express/examples/basic-starter-api-gateway-v1/node_modules/babel-core/lib/transformation/file/options/option-manager.js:368:12)
at compile (/Users/tylerfisher/src/serverless-express/examples/basic-starter-api-gateway-v1/node_modules/babel-register/lib/node.js:103:45)
at loader (/Users/tylerfisher/src/serverless-express/examples/basic-starter-api-gateway-v1/node_modules/babel-register/lib/node.js:144:14)
at Object.require.extensions. [as .js] (/Users/tylerfisher/src/serverless-express/examples/basic-starter-api-gateway-v1/node_modules/babel-register/lib/node.js:154:7)
at Module.load (internal/modules/cjs/loader.js:928:32)
at Function.Module._load (internal/modules/cjs/loader.js:769:14)
```

I've attempted to install `babel-plugin-transform-runtime`, which ends up with new errors:

```
Couldn't find preset "env" relative to directory "/Users/tylerfisher/src/serverless-express/examples/basic-starter-api-gateway-v1/node_modules/regenerator-transform" (While processing preset: "/Users/tylerfisher/src/serverless-express/examples/basic-starter-api-gateway-v1/node_modules/babel-preset-es2015/lib/index.js")
```

Installing `babel-preset-env` results in yet another error that I can't get past:

```
Error: Options {"loose":true} passed to /Users/tylerfisher/src/serverless-express/examples/basic-starter-api-gateway-v1/node_modules/babel-preset-env/lib/index.js which does not accept options. (While processing preset: "/Users/tylerfisher/src/serverless-express/examples/basic-starter-api-gateway-v1/node_modules/babel-preset-env/lib/index.js") (While processing preset: "/Users/tylerfisher/src/serverless-express/examples/basic-starter-api-gateway-v1/node_modules/babel-preset-env/lib/index.js") (While processing preset: "/Users/tylerfisher/src/serverless-express/examples/basic-starter-api-gateway-v1/node_modules/babel-preset-es2015/lib/index.js")
```

I'm not even sure at what point babel is invoked, so it's hard to trace down where to fix this issue.

Start by running `npm run setup` in the `basic-starter-api-gateway-v1` example and trace where the packaging process invokes Babel. Inspect the related Babel presets and plugins shown in the errors, including `babel-preset-es2015`, `babel-preset-env`, and `babel-plugin-transform-runtime`. Done means the standard example completes setup without manually installing additional Babel packages.

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