Enhance meter commands output

'meter-add' and 'meter-remove' . Currently these commands like many ONOS CLI commands return no output after completeion, so if a user wants to know what was the result of a command he or she needs to use another command. For example, after creating a meter with 'mweter-add' one needs to use 'meters' to see whether a meter was cteated or rejected by a switch. So, it would be useful if 'meter-add' produce some output like 'created meter id n' after a positive result, or 'failed to create a meter' after a negative attempt. Similar to 'meter-remove'