Added command set_params, that store params in a file
Now get params fom file if it exists and than by default
Covered set_params command by tests and added missing copyrights
Now there are two comands:
  server           whitch displays saved options;
  server:set    whitch save options in an file;
added method to display saved options
changed description
writed commands for server commands
have made changes, according to pull_request's comments
changed tests for server command
Added test to check that PARAMS_PATH constant should not be nil
Don't walk the stack to determine how to handle missing file.