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 #22

package.json

@@ -27,7 +27,7 @@
     "tslib": "2.1.0"
   },
   "devDependencies": {
-    "@softwareventures/tsconfig": "2.3.3",
+    "@softwareventures/tsconfig": "5.0.1",
     "@softwareventures/tslint-rules": "0.9.1",
     "ava": "3.15.0",
     "cz-conventional-changelog": "3.3.0",

yarn.lock

@@ -311,10 +311,10 @@
   dependencies:
     tslib "^1.9.3 || ^2.0.0"
 
-"@softwareventures/tsconfig@2.3.3":
-  version "2.3.3"
-  resolved "https://registry.yarnpkg.com/@softwareventures/tsconfig/-/tsconfig-2.3.3.tgz#29c619998a6b211180a78f34f0d417eb2eb75b0e"
-  integrity sha512-ymbE2zGMozyPLCDXAIrPU6AIMkQuTrAcdy1BRTkYU0rAE7FfNhyPAP3KHbIy/RzJ49HtIMt/RbPBwCWacSiPdw==
+"@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/tslint-rules@0.9.1":
   version "0.9.1"
@@ -4375,7 +4375,6 @@ npm@^6.14.9:
     cmd-shim "^3.0.3"
     columnify "~1.5.4"
     config-chain "^1.1.12"
-    debuglog "*"
     detect-indent "~5.0.0"
     detect-newline "^2.1.0"
     dezalgo "~1.0.3"
@@ -4390,7 +4389,6 @@ npm@^6.14.9:
     has-unicode "~2.0.1"
     hosted-git-info "^2.8.8"
     iferr "^1.0.2"
-    imurmurhash "*"
     infer-owner "^1.0.4"
     inflight "~1.0.6"
     inherits "^2.0.4"
@@ -4409,14 +4407,8 @@ npm@^6.14.9:
     libnpx "^10.2.4"
     lock-verify "^2.1.0"
     lockfile "^1.0.4"
-    lodash._baseindexof "*"
     lodash._baseuniq "~4.6.0"
-    lodash._bindcallback "*"
-    lodash._cacheindexof "*"
-    lodash._createcache "*"
-    lodash._getnative "*"
     lodash.clonedeep "~4.5.0"
-    lodash.restparam "*"
     lodash.union "~4.6.0"
     lodash.uniq "~4.5.0"
     lodash.without "~4.4.0"