Enter key sends command

Sending a command also clears the field.

octoprint/static/js/ui.js

@@ -1490,6 +1490,14 @@ $(function() {
                     contentType: "application/json; charset=UTF-8",
                     data: JSON.stringify({"command": command})
                 })
+            	$("#terminal-command").val('')
+            }
+            
+        })
+
+        $("#terminal-command").keyup(function(event){
+	    if(event.keyCode == 13){
+                $("#terminal-send").click()
 	    }
         })