Added a new spin function (nodelet_spin) to be used in nodelet nodes where the ros::spin function call is not required.

Set the diagnostic_period in the constructor. Used its value to control the sleep in the local spin function.

Kinetic format 2

See merge request !2

Merge branch 'kinetic_migration' of ssh://gitlab.iri.upc.edu:2202/labrobotica/ros/iri_core/iri_base_driver into kinetic_migration

This exaplins that the output rate of drivers doubled the desired one.

This reverts commit 5da8340c.

Added Hook functions for the post start and pre stop actions.
Added a default ros::nodeHandle al the classs constructor.

Integrated the necessary features of the deprecated ROS driver_base node into the iri_base driver node.
Initial testing successfull.

Changes to the iri_base_driver package for correct compilation under catkin. 

Solved some problems in the CMakeLists.txt file in the iri_base_driver package.

The main node thread sleep took effect only when the driver was running. In case the initialization failed, the node wastes 100% of the CPU.