New parameter jump_dir to set a directory where the files to be transferred are stored

Current Situation
If you use Jade with a jump host then it creates a temporary subfolder with a unique name in /tmp/ where the files to be transferred are stored.

Desired Behavior
The new option jump_dir set the location of a directory where JADE creates the temporary subfolder to store the files to be transferred. The default value of this option is /tmp/.