Report vuln for apache_mod_cgi_bash_env

Now with fewer false positives! It's kinda like a check method.
Improve false positive check
Add protip to description

This gets you lots of shells.
Add missed mixin
Fix missed var
Fix typo in description

Running on fumes here...
Reimplement old check code I was testing before

I would like to credit @wchen-r7 for providing advice and feedback.

@jvazquez-r7, too! :)
Favor check_host for a scanner
Fix description to be less lulzy
Land #3884, @wvu's check and reporting for apache_mod_cgi_bash_env