Add tasks for all the new languages

Task/Echo-server/Nim/echo-server.nim

@@ -0,0 +1,18 @@
+import asyncnet, asyncdispatch
+
+proc processClient(client: AsyncSocket) {.async.} =
+  while true:
+    let line = await client.recvLine()
+    await client.send(line & "\c\L")
+
+proc serve() {.async.} =
+  var server = newAsyncSocket()
+  server.bindAddr(Port(12321))
+  server.listen()
+
+  while true:
+    let client = await server.accept()
+    discard processClient(client)
+
+discard serve()
+runForever()