Start introduction of JSLint for JavaScript

**Description**

This is a test variant of using JSLint to check for JavaScript syntax and style mistakes. Ideally, it would benefit if all JS files in the future have JSLint configuration information at the top of the file which will allow for JSLint-configured editor to use JSLint to make JS code standard and error-free.

Why JSLint configuration at the top of the file? Because JSLint will be checking each JS file in precisely the same way on all of the different machines for each developer. We need consistency. If each developer will use his own set of rules for JSLint then obviously the effect of uniformity will be lost.

**Reviewers**
- @polesye