Enable websocket debugging.

kobalt/src/Build.kt

@@ -104,9 +104,7 @@ val kobaltPluginApi = project {
                 "com.squareup.retrofit2:converter-gson:${Versions.retrofit}",
                 "com.beust:jcommander:1.48",
                 "org.eclipse.jgit:org.eclipse.jgit:4.5.0.201609210915-r",
-
-//                "org.slf4j:slf4j-nop:${Versions.slf4j}",
-//                "org.slf4j:slf4j-api:${Versions.slf4j}",
+                "org.slf4j:slf4j-simple:${Versions.slf4j}",
                 *mavenResolver("api", "spi", "util", "impl", "connector-basic", "transport-http", "transport-file"),
                 "org.apache.maven:maven-aether-provider:3.3.9"
         )

src/main/kotlin/com/beust/kobalt/app/remote/KobaltServer.kt

@@ -21,6 +21,10 @@ import javax.annotation.Nullable
  *
  * The callbacks are used to initialize and clean up the state before and after each command, so that Kobalt's state
  * can be properly reset, making the server reentrant.
+ *
+ * To enable websocket debugging, launch with:
+ *   -Dorg.slf4j.simpleLogger.defaultLogLevel=debug
+ * More logging documentation: https://www.slf4j.org/apidocs/org/slf4j/impl/SimpleLogger.html
  */
 class KobaltServer @Inject constructor(@Assisted val force: Boolean, @Assisted @Nullable val givenPort: Int?,
         @Assisted val initCallback: (String) -> List<Project>,