Simplified the reproduction of attacks

All attacks now have a default directory inside the results/ directory
where the resulting attack files are saved. The location of these
directories can be set in the framework configuration file.
Renamed pdfrate_submitter.py into pdfrate_submit.py in reproduction/
Fixed bugs in mimicus library configuration

mimicus/config.py now tests for the existence of directories
before creating them. Wrong variable names in mimicus/default.conf
were corrected.