Bug: IIS Extraction script missing case handling

[righettod]

Add the following cases handling:

• [x] Check that the user running the script has local admin rights.
• [x] Ensure that that JSON generated is encoded in UTF8 and not UT8 BOM.

Error when JSON file is encoded using UTF8 BOM

PS> python main.py -f E:\Temp\TEST -s IIS -t template_html -o report.html
[INFO ] Load the audit rules from the reference file 'references/IIS.json'...
[INFO ] 54 rules loaded.
[INFO ] Gather the list of configuration files to review...
[INFO ] 1 files identified.
[INFO ] Load the configuration content for each configuration files to review...
[ERROR] Error during the processing: Expecting value: line 1 column 1 (char 0)

[righettod]

Error was also documented in a new KB section.