rfe: improve system php updates
Upon new installation, the installer detects correct system php version/settings for the OS and saves them in server config; when the system php is updated (eg. php5 -> php7), the installer does not subsequently detect the change and update server config. This change should be easy to detect and update settings correctly. Perhaps have a select list or checkbox PHP Settings to use system default or custom values (which would hide/show the custom fields when changed), and if the "use system defaults" setting is indicated, the installer can simply update the PHP Settings every time it is run, no need to track if the old values were previous defaults.
This issue derives from the discussion at https://www.howtoforge.com/community/threads/error_reporting-not-respected-in-custom-php-ini.82019/#post-388811