Impement timeout on heavy dataset tests

[Mstrutov]

Some algorithms may process some datasets for an extremely long time, therefore one test case can delay the following ones (the user will have to wait through the heavy test).

A possible solution: https://stackoverflow.com/a/31766591, http://antonlipov.blogspot.com/2015/08/how-to-timeout-tests-in-gtest.html.