Add a Platform 2.0 is running page

At the end of successful installation of Platform 2.0, the user should see the following message
200 OK
<h1>OpenMRS Platform ${version} is running.</h1>
<p>If you seeing this page, it means that the OpenMRS Platform is running successfully, but no user interface module is installed. To learn about the available user interfaces, see [an OpenMRS wiki page we need to create about this]</p>
<p>If you are a developer, you can access the REST API. [link to REST documentation]</p>

p.s. : https://talk.openmrs.org/t/what-should-the-platform-is-running-page-look-like/3644