Update binding.gyp for libsass refactor

Add in comments for the rebuild.js file, and include support to auto-rebuild on linux as well.

Since this was reverted (and I/we now know why) I have added
documentation as to avoid the issue re-occuring in the future.

This reverts commit dd6fcd0f.

Revert "remove install section from package.json, and rebuild.js. npm executes binding.gyp automatically. ref https://npmjs.org/doc/json.html"

This reverts commit cfe6e89a.

installation failes on windows : --msvs_version npm flag ignored during binding build

remove install section from package.json, and rebuild.js. npm executes binding.gyp automatically. ref https://npmjs.org/doc/json.html

CLI Cleanup

Add in support for debug information in the output css files.

Error on linux

submodule update to allow variables in media queries