Rename and Update .eslintrc config file. Fixes #230. Props @Cheffheid

* Rename .eslintrc config file to .js

* Add JS syntax to set ESLint config

* Add WP codestyle rules to ESLint config file

.eslintrc.js

@@ -0,0 +1,78 @@
+module.exports = {
+	"env": {
+		"browser": true,
+		"jquery": true,
+		"es6": true,
+	},
+	"extends": "wordpress",
+	"installedESLint": true,
+	"plugins": [],
+	"rules": {
+		// Enforce spacing inside array brackets
+		'array-bracket-spacing': ['error', 'always'],
+		// Enforce one true brace style
+		'brace-style': 'error',
+		// Require camel case names
+		'camelcase': ['error', {
+			properties: 'always'
+		}],
+		// Disallow or enforce trailing commas
+		'comma-dangle': ['error', 'never'],
+		// Enforce spacing before and after comma
+		'comma-spacing': 'error',
+		// Enforce one true comma style
+		'comma-style': ['error', 'last'],
+		// Encourages use of dot notation whenever possible
+		'dot-notation': ['error', {
+			allowKeywords: true,
+			allowPattern: '^[a-z]+(_[a-z]+)+$'
+		}],
+		// Enforce newline at the end of file, with no multiple empty lines
+		'eol-last': 'error',
+		// Require or disallow spacing between function identifiers and their invocations
+		'func-call-spacing': 'off',
+		// Enforces spacing between keys and values in object literal properties
+		'key-spacing': ['error', {
+			beforeColon: false,
+			afterColon: true
+		}],
+		// Enforce spacing before and after keywords
+		'keyword-spacing': 'error',
+		// Disallow mixed "LF" and "CRLF" as linebreaks
+		'linebreak-style': ['error', 'unix'],
+		// Enforces empty lines around comments
+		'lines-around-comment': ['error', {
+			beforeLineComment: true
+		}],
+		// Disallow mixed spaces and tabs for indentation
+		'no-mixed-spaces-and-tabs': 'error',
+		// Disallow use of multiline strings
+		'no-multi-str': 'error',
+		// Disallow multiple empty lines
+		'no-multiple-empty-lines': 'error',
+		// Disallow use of the with statement
+		'no-with': 'error',
+		// Require or disallow an newline around variable declarations
+		'one-var-declaration-per-line': ['error', 'initializations'],
+		// Enforce operators to be placed before or after line breaks
+		'operator-linebreak': ['error', 'after'],
+		// Require or disallow use of semicolons instead of ASI
+		'semi': ['error', 'always'],
+		// Require or disallow space before blocks
+		'space-before-blocks': ['error', 'always'],
+		// Require or disallow space before function opening parenthesis
+		'space-before-function-paren': ['error', 'never'],
+		// Require or disallow space before blocks
+		'space-in-parens': ['error', 'always', {exceptions: ['{}', '[]']}],
+		// Require spaces around operators
+		'space-infix-ops': 'error',
+		// Require or disallow spaces before/after unary operators (words on by default, nonwords)
+		'space-unary-ops': ['error', {
+			overrides: {'!': true}
+		}],
+		// Requires to declare all vars on top of their containing scope
+		'vars-on-top': 'error',
+		// Require or disallow Yoda conditions
+		'yoda': ['error', 'always']
+	}
+}