Add linting

[ghost]

• Eslint standard configuration (Airbnb and google will not be used yet).
• Eslint script in package.json.
• Pre-commit hook not to have unformatted code after each commit. This should avoid commit messages like "make the linter happy again" :)

[dtobe]

A few minor things.
Personally, I find spaces after function names ugly.
Also, the commas after the last element of a list or object.

[ghost]

A few minor things.
Personally, I find spaces after function names ugly.

Yes. I added a rule for that. Now we should not include spaces after function names.

Also, the commas after the last element of a list or object.

I think we could have pros if we do it like that. Think about writting code and using shortcuts to get line duplicates faster.

/cc @dtobe

[dtobe]

Do you want to add linting as a build command in the travis-file?

[ghost]

Do you want to add linting as a build command in the travis-file?

@dtobe It is also an option. I would just prefer to keep it as a pre-commit command and see if we get use to it. This will avoid linting problems during building.