Remove priority_level from yaml file

It is not currently used for anything, will revert when that time comes.

userspace/digwatch/configuration.h

@@ -95,7 +95,6 @@ class digwatch_configuration
 	void init(std::string conf_filename);
 	void init();
 	std::string m_rules_filename;
-	std::string m_priority_level;
 	std::vector<output_config> m_outputs;
  private:
 	yaml_configuration* m_config;