Better detection for AGS Script and AsciiDoc asc files

Went into the Explore languages feature within github to see the "AGS Script" projects and noticed a couple of things:

 1. .asc files were getting marked as AGS Script but formatted as AsciiDoc
 2. .asc files that were neither format were also getting marked as AsciiDoc.

So, I added a heuristics checker for .asc files. Additionally, because AGS Script is a nameless language  designed specifically for the Adventure Game Studio tool (and mentioned as `'C'-style script` within the AGS source code, but no one calls it that), I renamed the script to Adventure Game Studio to avoid ambiguity (similar to how the ColdFusion's language is called ColdFusion), and brings more clarity to Adventure Game Studio game projects within github.

After making these changes, I cloned a selection of the projects that were incorrectly marked as AGS Script and ran a `exec rake linguist <clone_path> --breakdown` on them to ensure that things were working properly.