changed some common mysql functions

- renamed construct_mysql() to construct_mysql_options().
- added mysql_dump() function in order to simplify SaveInstallTest.
fix typos in comments of prepareTask test
mark another test as incomplete

- The getDevicesToInventory() test doesn't assert anything and triggers
  too much notices.
- moved mark_incomplete() calls at the end of methods in order to avoid
  test bypass.
add verbose in addition of debug for PHPUnit

This allows to show more usefull information in console logs like how
many tests are actually skipped or incomplete.