Merge pull request #345 from jeff1evesque/php_load_dataset

#342: Return JSON from 'load_dataset.php'
#346: ajax_data.js, remove unnecessary 'console.log()'
Merge pull request #347 from jeff1evesque/js_ajax_data

#346: Remove unnecessary 'console.log()'
#342: load_dataset.php, add missing semicolon