ckeditor is now included as a submodule

Added ckeditor stable as a submodule to htdocs/js/ckeditor
Added a gitignore so that the files generated by the setup script don't get added to the repo in future.
Also included the the cached template folder 'template_c' so that doesn't get included either

 Changes to be committed:
* new file:   .gitignore
* new file:   .gitmodules
* new file:   htdocs/js/ckeditor

See merge request !3