BasicManagement Ping: add ping command support

- Add the ping command support: build and call the system command,
parse its result output.
- Fix a typo in update_test_ids_lists() funtion in file
rygel-basic-management.vala

Signed-off-by: Christophe Guiraud <christophe.guiraud@intel.com>
Merge pull request #8 from cguiraud/dev-ping-v2

BasicManagement Ping: add ping command support - v2