fix console printer to also print unknown levels

this can happen if people added their own log4cxx levels
In this case, still print the message on the console in red with "UNKNO" level instead of just printing a newline.

src/rosconsole/rosconsole.cpp

@@ -335,7 +335,7 @@ void Formatter::init(const char* fmt)
 
 void Formatter::print(void* logger_handle, ::ros::console::Level level, const char* str, const char* file, const char* function, int line)
 {
-  const char* color = NULL;
+  const char* color = COLOR_RED;
   FILE* f = stdout;
 
   if (level == levels::Fatal)
@@ -362,8 +362,6 @@ void Formatter::print(void* logger_handle, ::ros::console::Level level, const ch
     color = COLOR_GREEN;
   }
 
-  ROS_ASSERT(color != NULL);
-
   std::stringstream ss;
   ss << color;
   V_Token::iterator it = tokens_.begin();