Inherited Enumberable Prop checks, variable for declared strong attrs, and Docs

[jnhuynh]

Added new lines for easier visual code logical segment detection.

Added function to use for ... in to check for declaredStrongAttrsKey on target. for ... in iterates over inherited enumerable properties while hasOwnProperty only checks the object's direct properties.

• https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/for...in

JSHint has no intention of support ES7 decorators for awhile so I added that to the README.

• https://github.com/jshint/jshint/issues/2297
• https://github.com/jshint/jshint/issues/2310
• http://jshint.com/blog/new-lang-features/

Add initial docs to README.

[lukemelia]

Awesome! Thanks, @jnhuynh!