Fix for npm run dev problems

[leedriscoll]

Webpack has chaged their definition from output to outputOptions in webpack/webpack#7232, webpack/webpack@3a896c9#diff-03af1a9344cf93838ad925ff61de02aaL328

This is causing the the error shown below when trying to run npm run dev on this repo.

The recommended fix is to upgrade the webpack-cli dev dependency.

This PR has taken the oppourtunity to upgrade webpack, webpack-cli and webpack-dev-server dev dependencies to get them all on the latest versions.

❯ npm run dev

> @ dev /Users/lee/Desktop/webpack-starter
> cross-env NODE_ENV=development webpack-dev-server

/Users/lee/Desktop/webpack-starter/node_modules/webpack-cli/bin/config-yargs.js:89
				describe: optionsSchema.definitions.output.properties.path.description,
				                                           ^

TypeError: Cannot read property 'properties' of undefined
    at module.exports (/Users/lee/code/webpack-starter/node_modules/webpack-cli/bin/config-yargs.js:89:48)
    at Object.<anonymous> (/Users/lee/code/webpack-starter/node_modules/webpack-dev-server/bin/webpack-dev-server.js:84:40)
    at Module._compile (internal/modules/cjs/loader.js:689:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:700:10)
    at Module.load (internal/modules/cjs/loader.js:599:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:538:12)
    at Function.Module._load (internal/modules/cjs/loader.js:530:3)
    at Function.Module.runMain (internal/modules/cjs/loader.js:742:12)
    at startup (internal/bootstrap/node.js:266:19)
    at bootstrapNodeJSCore (internal/bootstrap/node.js:596:3)
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! @ dev: `cross-env NODE_ENV=development webpack-dev-server`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the @ dev script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

npm ERR! A complete log of this run can be found in:
npm ERR!     /Users/lee/.npm/_logs/2018-10-17T12_42_04_824Z-debug.log

[spenwall]

This worked better for me. I was getting the same error until I upgraded webpack dependencies.

[DiegoArrieta]

Thanks! @leedriscoll