Unit Tests

- Added proper handling for when no command or filter is specified, and
  no rc.default.command exists.
- Improved wording on above error message.
- Fixed typo in previous commit (managed to check in code before the
  build completed, and ultimately failed).
- Now reports errors that occur during initialization at the same level
  of verbosity as during command execution.

src/Task.cpp

@@ -955,7 +955,7 @@ void Task::validate () const
 
   if (has ("priority"))
   {
-    std::string priority - get ("priority");
+    std::string priority = get ("priority");
     if (priority != "H" &&
         priority != "M" &&
         priority != "L")