change target to es5 to work on IE

#1

Author: vesapupovci

package.json

@@ -22,7 +22,7 @@
     "setup": "npm install -g semantic-release-cli && semantic-release-cli setup",
     "lint": "tslint  --project tsconfig.json -t codeFrame 'src/**/*.ts' 'test/**/*.ts'",
     "prebuild": "rimraf dist",
-    "build": "tsc --module commonjs && rollup -c rollup.config.ts && typedoc --out docs --target es6 --theme minimal --mode file src",
+    "build": "tsc --module commonjs && rollup -c rollup.config.ts && typedoc --out docs --target es5 --theme minimal --mode file src",
     "start": "rollup -c rollup.config.ts -w",
     "test": "jest --coverage",
     "test:watch": "jest --coverage --watch",