Subscribers parmeters in YAML

The current implementation of the ParamServer (actually, the ParserYAML, btw not following naming convention) does not allow the subscribers to have specific parameters.

In GAUSS we require this feature and I think it could be useful.

The problem is that a "unique_name" should be defined for the ROS subscribers. Now they have package, topic, type and sensor_name. Package and type can't be unique (two cameras should work at the same time with two different subscribers). I think that both topic and sensor_name should be always unique. Considering strange cases such as GNSS (two or three different types of captures are used in the same sensor), I think that topic is the best unique key. We could add a "name" but I think that's excessive.

This is core code but it is only used in ROS.