Implement support to the SCRIPT_* variables in libmodsecurity

[zimmerle]

The following variables needs to be implemented inside libModSecurity:

• SCRIPT_BASENAME
• SCRIPT_FILENAME
• SCRIPT_GID
• SCRIPT_GROUPNAME
• SCRIPT_MODE
• SCRIPT_UID
• SCRIPT_USERNAME

More information about these variables can be found at ModSecurity reference manual: https://github.com/SpiderLabs/ModSecurity/wiki/Reference-Manual

[zimmerle]

The set of variables SCRIPTS opens a very interesting discussion. Within v3 and it seamless approach, the rules while executed [should] produce the same response regardless of the server that is hosting the content or server configuration. That is not the case for the set of variables SCRIPTS, where the need of understanding server configuration (path, permission and so on) are needed. I also think that those variables could be replaced for different ones, within representation in the request itself, not on the server configuration. With that said, I am marking this issue as closed.