feat: compile to ES2017

BREAKING CHANGE: This library now uses ES2017 syntax. This breaks compatibility with Node < 8.10 and
very old browsers that do not support ES2017 syntax. If you need to support older browsers, then you
should use Babel to compile ES6+ code down to ES5.

closes #35

package.json

@@ -21,7 +21,7 @@
   "sideEffects": false,
   "devDependencies": {
     "@softwareventures/semantic-release-config": "1.1.1",
-    "@softwareventures/tsconfig": "4.1.0",
+    "@softwareventures/tsconfig": "5.0.1",
     "@softwareventures/tslint-rules": "0.9.2",
     "cz-conventional-changelog": "3.3.0",
     "semantic-release": "17.4.2",

yarn.lock

@@ -273,10 +273,10 @@
   dependencies:
     tslib "2.0.0"
 
-"@softwareventures/tsconfig@4.1.0":
-  version "4.1.0"
-  resolved "https://registry.yarnpkg.com/@softwareventures/tsconfig/-/tsconfig-4.1.0.tgz#31dbe9b733bc5ca45aa8ee45b032d114695f46a7"
-  integrity sha512-S27RcoTBaqvhmXmAwH/OVSAuAm7fMSpK62gLwP3Cta8RpSLdNUYsmhNEI9gkx3JrR5Dh1k6lVdfR37vMKXiiYw==
+"@softwareventures/tsconfig@5.0.1":
+  version "5.0.1"
+  resolved "https://registry.yarnpkg.com/@softwareventures/tsconfig/-/tsconfig-5.0.1.tgz#9be2d6dcdc3de65233014c527754700f46882bbb"
+  integrity sha512-B1LBY+S7dDiPmH29MTi3Z3hBdSEetHf87cmUueQCSlrbpFpROZvDZrnujM844wXKNue5XYIe5oO8jp/eWCfY9w==
 
 "@softwareventures/[email protected]":
   version "0.9.2"