feat: move umd bundle up and out of the dist directory

BREAKING CHANGE:
The umd path for system.js users has changed from:
```
node_modules/angular-calendar/dist/umd/angular-calendar.js
```

to
```
node_modules/angular-calendar/umd/angular-calendar.js
```

README.md

@@ -72,7 +72,7 @@ You can find quick start examples for all common module bundlers in the [build-t
 ### Usage without a module bundler
 
 ```html
-<script src="node_modules/angular-calendar/dist/umd/angular-calendar.js"></script>
+<script src="node_modules/angular-calendar/umd/angular-calendar.js"></script>
 <script>
     // everything is exported angularCalendar namespace
 </script>

webpack.config.umd.ts

@@ -99,7 +99,6 @@ export default {
       failOnError: true
     }),
     new ExtractTextPlugin('./../css/angular-calendar.css'),
-    new ExtractTextPlugin('./../dist/css/angular-calendar.css'),
     new webpack.SourceMapDevToolPlugin({
       filename: 'angular-calendar.js.map',
       test: /\.js($|\?)/i