update linter from jscs to eslint

[sgnl]

added a new branch: feature/eslint

main linter configuration goes into index.js

I also added two more files named: node.js and browser.js these files are supplemental and meant to extend the main configuration.

• index.js will contain general styles, no pre-defined globals
• browser.js will contain browser specific settings, pre-defined globals are okay (console, document, etc)
• node.js will contain server-side specific settings (process)

[sgnl]

future: npm namespace publish @devleague/eslint-[env] e.g. @devleague/eslint-node.