Migration to ES6

[UlisesGascon]

Migration to ES6 🎉

Context:

Original issue: #152
Release Target: 1.5

Notes

• This PR is an addition to many previous efforts. I just made a big step in this PR.
• Most parts are now under a fresh JS Sintaxis! But not all of them
• The missing parts are covered in separate PRs (like templates or Grunt) due migrations/deprecations, etc...
• The logic can be better but we don't have yet unit testing and I don't want to refactor DAOs and routes before Unit tests are implemented (see Roadmap for 2019-2020 #148)
• Upgraded docker images to v12 for testing (Docker compose) (See: e89dab4)

Changelog

• a5c959d WIP. Migration ES6: Server by @UlisesGascon
• a779d68 Migration ES6: Config by @UlisesGascon
• a8ddafd Migration ES6: Artifacts by @UlisesGascon
• cad7959 WIP. Migration ES6: DAOs by @UlisesGascon
• d5b6976 Migration ES6: DAOs by @UlisesGascon
• cbb07db Migration ES6: Typos by @UlisesGascon
• 4fcc9df Migration ES6: Routes by @UlisesGascon
• 4b685ec Fix routes by @UlisesGascon
• 1389257 typo by @UlisesGascon
• d7ad952 Fixed missing argument in errorHandler by @UlisesGascon

  Error-handling middleware always takes four arguments. You must provide four arguments to identify it as an error-handling middleware function. Even if you don’t need to use the next object, you must specify it to maintain the signature. Otherwise, the next object will be interpreted as regular middleware and will fail to handle errors. Source: Express Docs

• 328a1f9 Added missing condition by @UlisesGascon
• e89dab4 Upgrade docker images to Nodejs 12 by @UlisesGascon

[UlisesGascon]

Ready for review @lirantal @ckarande 👍

[UlisesGascon]

Merged due #187