Added init of variables to copy_avrdude.py

Added initialization of avrdude_name, platform_folder and files
variables to copy_avrdude.py, to fix several errors:

File "copy_avrdude.py", line 49, in <module>
for file in files:
NameError: name 'files' is not defined

and

File "copy_avrdude.py", line 45, in <module>
if not os.path.isfile(os.path.join(path_to_firmware, avrdude_name)):
NameError: name 'avrdude_name' is not defined