Update notes for submitted changes

* merged RHEL6 kickstart into default kickstart
* merged Fedora and RHEL7 kickstarts into a 'default' kickstart
* replaced remaining distro conditionals with feature test variables
* move 'yum' ksmeta to OSMajor.default_install_options
* new OSMajor.default_install_options method for detected ks meta variables
* conditionalise snippets based on whether the relevant config file exists
* replace distro conditionals for curl/wget with a wrapper function
* enable chrony services in %post, instead of using 'services' command
* don't hide output from chkconfig
* tests: negative test for bootloader --leavebootorder option