[profiles] Fix typo in OWTF-IG-002 command.

Fix a typo in the shell command which generates Metagoofil's html report as
'semipassivemetagoofil_report.html' instead of
'semipassive/metagoofil_report.html'.
[core] Fix UnicodeError in utf-8 decoding.

Add 'replace' parameter when calling str.decode('utf-8') in order to avoid
possible "UnicodeDecodeError: 'utf8' codec can't decode byte 0xfe in position
9252: invalid start byte"-like error messages.