Made dependency on Jetty's websocket-api artifact explicit.
This makes possible to build from within the module with a Jetty
version specified via -Djetty-version=...
<artifactId>jetty-servlets</artifactId>
<version>${jetty-version}</version>
</dependency>
+ <dependency>
+ <groupId>org.eclipse.jetty.websocket</groupId>
+ <artifactId>websocket-api</artifactId>
+ <version>${jetty-version}</version>
+ </dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-log4j12</artifactId>
