Add /iot/groups routes to manager

[mapedraza]

When merged telefonicaid/iotagent-node-lib#1648, would be interesting to add the new alternative paths for configuring service groups to this component.

The Idea is to add the following routes:

• POST /iot/groups -> create a new configuration group
• GET /iot/groups -> get configuration group
• etc.

As an alternative (additionally) to:

• POST /iot/services -> create a new configuration group
• GET /iot/services -> get configuration group
• etc.

Original Issue: telefonicaid/iotagent-node-lib#752

[fgalan]

I see two proxy alternatives:

1. Keep the same URL in the mappings:
   • POST IOTAMan/iot/configGroups -> POST /IOTA/iot/configGroups
   • POST IOTAMan/iot/services-> POST /IOTA/iot/services
   • etc.
2. Collapse to use always the no obsolete one at IOTA
   • POST IOTAMan/iot/configGroups -> POST IOTA/iot/configGroups
   • POST IOTAMan/iot/services-> POST IOTA/iot/configGroups
   • etc.

The second one could be complex if, apart from URL mapping, some transformation has to be done in the payload (I'm not sure but I suspects that /iot/configGroups and /iot/services use different root key in JSON payload).