Add file footer for ELPA compatibility

This commit makes js-doc.el installable with package.el.

- Add footer line
- Add Commentary section
- Add Code section
- Replace X-URL header with URL header
Add missing require form
Add autoload cookies
Merge pull request #4 from yasuyk/add-autoload-cookies

Add autoload cookies
Merge pull request #2 from yasuyk/add-file-footer

Add file footer for ELPA compatibility
Merge branch 'add-require' of https://github.com/yasuyk/js-doc into yasuyk-add-require

Conflicts:
	js-doc.el