Add echo application

Simply echoes its arguments - for testing purposes

build.sbt

@@ -479,6 +479,9 @@ lazy val okhttp = project
     )
   )
 
+lazy val echo = project
+  .settings(commonSettings)
+
 lazy val jvm = project
   .aggregate(
     coreJvm,
@@ -491,7 +494,8 @@ lazy val jvm = project
     `sbt-launcher`,
     doc,
     `http-server`,
-    okhttp
+    okhttp,
+    echo
   )
   .settings(commonSettings)
   .settings(noPublishSettings)

echo/src/main/scala/coursier/echo/Echo.scala

@@ -0,0 +1,5 @@
+
+object Echo {
+  def main(args: Array[String]): Unit =
+    println(args.mkString(" "))
+}