Simplify tests for stdin

Closes gh-596
Fixes #547
Add checkStdin method

Closes gh-594
Fixes #577
Add "safeContextKeyword" to jscs config
Tests: stdin data should pass the supplied config

Closes gh-607
Fix our violations of disallowMultipleVarDecl
Enhance google's preset

Closes gh-609
Fixes #506
Add additional comment to google preset test
Prepare for version 1.6.0
1.6.0
Build: fix browserify build script
Contributing Guide: Add alphabetical note to preset instructions.
Airbnb preset. Fixes #471
Tests: rename misnamed file.
Avoid node.js 0.10.x exit code bug for MS Windows

Fixes #587

see also:
https://github.com/joyent/node/issues/3584
Add rewire method to properly stub dependency

Closes gh-613
Add direct unit tests for options/preset
Dependencies: bump separated-coverage to a more colorblind friendly version
Tests: Add direct tests for test/utils.js
Docs: Update packages and extensions sections with new URLs.
Docs: Update grunt-jscs URL.