Add shell script to package extension for install

This will add a shell script that will package the extension for install into the CMS.  To package, on a *nix system, navigate to the `build` folder and run `./build.sh`.  When complete, you will have an installable `.zip` file under `build/packages`.

Included with this are a couple of miscellaneous changes:

- The component manifest is moved to the installed location, following suit with all other files in the repo
- The component manifest is updated to allow proper install of the extension
- The packages submenu item is uncommented from the manifest, as was done with the submenu helper in #21
- A component script is added which checks the minimum supported CMS version; as it was decided that 3.3 is needed for this, that is the version being checked