Add ESLint and Prettier configs; Apply linting;

[ylv-io]

The PR introduce ESLint and Prettier support 🍾

• Linting is set up on a pre commit hook so it is impossible to commit code without compiling and linting it
• There are base configs for both ESLint and Prettier
• Editor extension are available for prettier so a code will be formatted on every save

Only cli and lib projects are linted at that moment and warnings are ignored. We have to try this config first and make sure we are comfortable with it. Next steps are:

• Linting tests as well
• Linting other projects
• Fixing warnings

I belive that code consistency is more important than personal preferences yet I want to be absolutely sure that you guys – @spalladino and @jcarpanelli are comfortable with these rules. Let me know if anything feels wrong and we'll figure it out.

PS As @spalladino requested semicolons are in.

[spalladino]

I'm going to blindly approve this one, as I refuse to go through 24k added lines :-P

The config files look good. One change I'd like to see though: can we remove the tslint dependency from the root package.json?

[ylv-io]

Absolutely we'll remove it!