Merge pull request #298 from jeff1evesque/doc_linux_packages

#292: Documentation: Install Python's 'magic' module
Merge pull request #299 from jeff1evesque/doc_linux_packages

#292: README.md, remove single quotes
#282: load_dataset.php, define 'foreach' skeleton-loop
#282: load_dataset.php, define 'file_name', 'file_temp' in foreach
#282: load_dataset.php, remove 'local variables'
#282: load_dataset.php, add 'local variables'
#282: load_dataset.php, minor comment
#282: load_dataset.php, properly add file properties to associative array
#282: load_dataset.php, add 'json_creator' to 'arr_upload'
#282: load_dataset.php, JSON encode 'arr_upload' array
#282: load_dataset.php, remove 'JSON encode file upload'
#282: load_dataset.php, properly add uploaded file properties to 'arr_upload'
#282: load_dataset.php, add 'upload quantity' to 'arr_upload'
#282: load_dataset.php, 'unset(index)' since no longer needed
#282: load_dataset.php, do not print number of upload files
#282: load_dataset.php, 'count()' more reliable than 'index'
#282: load_dataset.php, properly define associative array
#282: load_dataset.php, properly call 'index' variable
#282: load_dataset.php, change semicolon to comma (typo)
#282: load_dataset.php, properly add to 'arr_upload' array