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