added missing initialization step in database::command
added missing initialization step in database::command

Closes #284

Signed-off-by: Adam Midvidy <2d7069863fd4b139702261e4b5e1fcfb66531ac6@gmail.com>

xdg/mongo-cxx-driver,mongodb/mongo-cxx-driver,acmorrow/mongo-cxx-driver,mongodb/mongo-cxx-driver,mongodb/mongo-cxx-driver,xdg/mongo-cxx-driver,xdg/mongo-cxx-driver,acmorrow/mongo-cxx-driver,acmorrow/mongo-cxx-driver,acmorrow/mongo-cxx-driver,xdg/mongo-cxx-driver,mongodb/mongo-cxx-driver