Update for Moodle 2.8
	modified:   README.md
	modified:   lib.php
	modified:   settings.php
	modified:   styles.css
	modified:   version.php
	modified:   yui/build/moodle-atto_chemistry-button/moodle-atto_chemistry-button-debug.js
	modified:   yui/build/moodle-atto_chemistry-button/moodle-atto_chemistry-button-min.js
	modified:   yui/build/moodle-atto_chemistry-button/moodle-atto_chemistry-button.js
	modified:   yui/src/button/js/button.js