add echo and simple chat

build.gradle

...otlin/de/thk/gm/websocketsdemo/configs/WebSocketConfig.kt

...de/thk/gm/websocketsdemo/controllers/WelcomeController.kt

...n/kotlin/de/thk/gm/websocketsdemo/handlers/EchoHandler.kt

...in/de/thk/gm/websocketsdemo/handlers/SimpleChatHandler.kt

src/main/resources/static/echoclient.html

src/main/resources/templates/index.ftlh

src/main/resources/templates/layout.ftlh

src/main/resources/templates/simpleChat.ftlh