title: Can py.test support multiple -k options?
body: <p>Can py.test supports multiple -k options?
  Each testcase belongs to a particular group such as _eventnotification or _interface, etc.
  Is it possible to run test cases that belong to either one or both at the same time?
  ie, run testcases that has _eventnotification or _interface in the name at the same time.
  I tried the following and only the testcases with _interface were executed.
  If that is not supported, is there another way to do this?</p>
  
  <p>py.test -k "_eventnotification" -k "_interface"</p>