nginx-nasxi: new package

nginx-nasxi: new package

Naxsi is a third party nginx module reads a small subset of simple rules
containing a list of known patterns involved in website vulnerabilities.
This module behaves like a DROP-by-default firewall for nginx.

Signed-off-by: Adam Duskett <aduskett@codeblue.com>
[Thomas:
 - include Config.in file directly from package/Config.in and not from
   package/nginx/Config.
 - improve Config.in help text with more details
 - rename the package prompt from ngx_http_naxsi_module to nginx-naxsi
 - remove NGINX_NAXSI_SOURCE, and fix the definition of
   NGINX_NAXSI_SITE
 - change license from GPLv3 to GPLv2+ with OpenSSL exception
 - cange license file from LICENSE to naxsi_src/naxsi_json.c. The
   LICENSE file exists in the latest Git master of the project, but
   not in the 0.54 tag that we're packaging.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>