1) Add support to testing Instance Manager in daemon mode;
2) Don't run Instance Manager tests when running with --ps-protocol option;


mysql-test/lib/mtr_cases.pl:
  WL#2789 "Instance Manager: test using mysql-test-run testing framework"
  Skip/disable Instance Manager tests in the following cases:
    - we are testing embedded server;
    - we are running with --ps-protocol;
    - Instance Manager executable does not exist;
  Report about the reason in the standard way.
mysql-test/lib/mtr_process.pl:
  WL#2789 "Instance Manager: test using mysql-test-run testing framework"
  Make several attempts (i.e. send several signals to process) while trying to kill it.
mysql-test/mysql-test-run.pl:
  WL#2789 "Instance Manager: test using mysql-test-run testing framework"
  Add support for testing Instance Manager in daemon mode.