[recording] solve name collissions

[floweisshardt]

when running multiple testsuite in the same package (e.g. with multiple CMake macros set to TRUE during catkin run_tests) there are name collission for

• recorded bag files ts*
• test results txt files ts*
• test results bag files ts*
• overall test results atf_result.txt, atf_result.bag

Solution:

• apply date/time suffix
• symlink latest recordings and test results to latest (for easy plotter terminal commands)