Add eslint and prettier back to repo

[alexandrebodin]

⚠️ We have stopped merging PRs for now to the Strapi core.


The reason is that we are developing new architecture for the admin panel and for the plugins.

This new architecture will provide stability of the Strapi core as we approach the release of Beta.

We appreciate and welcome all your contributions, but until further notice, please do not submit a PR as it will not be merged.

Furthermore, you will have to rewrite it based on the new architecture.

Description:

Adds eslint and prettier formatting with commit hooks

My PR is a:

• 💥 Breaking change
• 🐛 Bug fix #issueNumber
• 💅 Enhancement
• 🚀 New feature

Main update on the:

• Admin
• Documentation
• Framework
• Plugin

Manual testing done on the following databases:

• Not applicable
• MongoDB
• MySQL
• Postgres
• SQLite

[lauriejim]

LGTM