CRTK version query

[adeguet1]

As we plan to add features and commands to CRTK we need to add method(s) to query the version of CRTK supported by a given device. We need to decide:

• What format to use? Something like major.minor.patch or year.month?
• What would be the logic behind version numbers? If a new API breaks the oldest one, would that automatically be a major revision?
• Do we need to provide multiple commands for client and server? For example, if someone uses the Python ROS client code, should we provide device_crtk_version() and client_crtk_version()