Added eslint config.

Fixes #22.

.eslintrc

@@ -0,0 +1,45 @@
+env:
+    node: true
+
+ecmaFeatures:
+    templateStrings: true
+
+    classes: true
+
+    arrowFunctions: true
+    defaultParams: true
+    restParams: true
+    spread: true
+    superInFunctions: true
+    generators: true
+
+    blockBindings: true
+    destructuring: true
+    forOf: true
+
+    binaryLiterals: true
+    octalLiterals: true
+    unicodeCodePointEscapes: true
+
+    objectLiteralComputedProperties: true
+    objectLiteralShorthandMethods: true
+    objectLiteralShorthandProperties: true
+
+# Note: Rules are modified using a number that defines what the rule's behavior should be:
+# 0 - turn the rule off
+# 1 - turn the rule on as a warning (doesn't affect exit code)
+# 2 - turn the rule on as an error (exit code is 1 when triggered)
+rules:
+    semi: [2, "always"]
+    no-extra-semi: 2
+    semi-spacing: 2
+    comma-spacing: 2
+    strict: [1, "global"]
+    no-unused-vars: 1
+    no-use-before-define: [2, "nofunc"]
+
+    # Disabled:
+    no-underscore-dangle: 0
+    quotes: 0
+
+# vim: ft=yaml