Fix library header according to the GNU Emacs Manual

- fix a file header
- add `Package-Requires` header
- change Repository header to URL header
- add `Code` section
- add a footer line

For more information, See following URL

http://www.gnu.org/software/emacs/manual/html_node/elisp/Simple-Packages.html
http://www.gnu.org/software/emacs/manual/html_node/elisp/Library-Headers.html
Merge branch 'fix-library-header' of https://github.com/yasuyk/helm-css-scss into yasuyk-fix-library-header
Fix library header thanks yasuyk :)
Change comment type /__ / to /*__ */
Purge anything-css-scss.el