Obligate LinkInterfaces to implement getLinkConfiguration. 11ab9aa0 introduced a bug where TCP links would cause a crash loading the sensors page

* enable TCPLinkTest
* enable FileManagerTest

This mechanism automatically queues data into the correct thread where necessary, otherwise the method is invoked directly with low overhead.

At the same time remove the UDP socket event workaround. It is not a problem.

This way we don't need macro-magic to deal with
different operating systems and compilers.
Signed-off-by: Tomaz Canabrava <tomaz.canabrava@intel.com>