Update version strings, update NSIS file, move around extra files

The additional files packaged with the installer have been moved to
their own dir to separate them from the C++ source.

All licenses are now also included in the installer, as per the terms.

The version string in overlaycontroller.h has been updated to 2.8.0.

src/package_files/manifest.vrmanifest

@@ -0,0 +1,16 @@
+{
+	"source" : "builtin",
+	"applications": [{
+		"app_key": "matzman666.AdvancedSettings",
+		"launch_type": "binary",
+		"binary_path_windows": "AdvancedSettings.exe",
+		"is_dashboard_overlay": true,
+
+		"strings": {
+			"en_us": {
+				"name": "Advanced Settings",
+				"description": "OpenVR Advanced Settings Overlay"
+			}
+		}
+	}]
+}