Bug Fix - #382 task annotate doesn't complain when a task id is omitted

- added error msg when annotating without a task id

src/command.cpp

@@ -1887,6 +1887,9 @@ int handleAnnotate (std::string &outs)
     if (!context.task.has ("description"))
       throw std::string ("Cannot apply a blank annotation.");
 
+    if (!context.task.has ("id"))
+      throw std::string ("ID needed to apply an annotation.");
+
     std::stringstream out;
 
     std::vector <Task> tasks;