Tests: Warning: a promise was created in a handler but was not returned from it

[lesn1kk]

When we call native methods in order to stop advertising and listening and kill connections in teardown, we do not return any value, just call t.end(), which causes a Warning: a promise was created in a handler but was not returned from it, see http://goo.gl/rRqMUw at process._tickCallback (node.js:924:13) to appear.