Added API scanner tool

New tool for issue #171 which links to libxenia to dump the API usage
from packaged content

src/xenia/tools/api-scanner/README.md

@@ -0,0 +1,24 @@
+## api-scanner
+
+api-scanner will dump out the API imports from a packaged 360 game
+
+### Usage
+
+Run from the command line
+
+`api-scanner <package_path>`
+
+or:
+
+`api-scanner --target <package_path>`
+
+Output is printed to the console window, so it self-managed.
+
+The suggested usage is to append the output to a local file:
+
+`api-scanner <package_path> >> title_log.txt`
+
+### Issues
+
+- Duplicate code for loading containers
+- Several issues with gflags library - incorrectly prints usage from other files (due to linkage with libxenia)