README.md install

 * Need to move the install docs into INSTALL.md
 * Don't install apache2 and libapache2-php by default.  Have a seperate section show instructions for Caddy (and maybe Apache2 as a backup but perhaps someone should check out nginx instead due to SSE buffering)
 * Change the PHP runner to php-fpm - have it run as www.conf (defaults are okay)
 * Add config info on php-fpm www.conf
 