Backlog/112 alarms

Adds an Alarm document, finishing the issue https://github.com/telefonicaid/fiware-connectors/issues/112

It also adds new INFO traces needed by the alarm system.

A minor fix in the README has been done as well.
If I have to remove it from one of the two locations... I prefer to remove it from the README. I think this kind of information is more useful for a platform operator, thus must be here. What do you think?