Piwik.js tests: Replace JSLint with JSHint #7232
Description
Required to resolve #5960
JSHint is the community-driven version of JSLint and more up to date. I think it can even read jslint options so we wouldn't have to change much. JSHint is actively developed and offers fine-grained configuration.
A JS for the tests can be found here: https://github.com/jshint/jshint/blob/master/dist/jshint.js
JSHint also allows us to define more useful options like "Max Complexity", "Max Depth", "Max Params" etc