eslint refactor

- Related #15
- Migrated to Airbnb
- Removed dependency `eslint-config-imperative-es6`
- Added dependency `eslint-config-airbnb-base` and `eslint-plugin-import`

Author: UlisesGascon

.eslintrc

@@ -0,0 +1,38 @@
+{
+	"extends": "airbnb-base",
+	"parserOptions": {
+		"sourceType": "module",
+		"allowImportExportEverywhere": false,
+		"ecmaVersion": 2018
+	},
+	"env": {
+		"mocha": true,
+		"es6": true,
+		"node": true
+	},
+	"rules": {
+		"indent": [2, "tab"],
+		"no-tabs": 0,
+		"max-len": 0,
+		"no-underscore-dangle": 0,
+		"class-methods-use-this": ["off"],
+		"no-nested-ternary": ["off"],
+		"quotes": ["error", "single"],
+		"linebreak-style": ["error", "unix"],
+		"semi": ["error", "always"],
+		"no-use-before-define": [
+			"error",
+			{
+				"functions": false,
+				"classes": false
+			}
+		],
+		"arrow-parens": [
+			"error",
+			"as-needed",
+			{
+				"requireForBlockBody": false
+			}
+		]
+	}
+}