You can now define your custom repos with the `%FEDORA_VERSION%` variable, to automatically use the correct repo version, so that you never have to maintain their custom URLs again in the future.
You can now easily remove RPMs from your custom image, without having to edit the build.sh script.
This also changes the old "rpms" config key, to "rpm-install", for consistency with the new setting.
Thanks to leveraging Bash arrays, we are now able to use parameter expansion to perform every package installation as one rpm-ostree operation instead of individual ones. This will give us a huge build speedup.
Bash properly expands every array element as safely quoted arguments, complete with support for spaces and special characters.
This new technique is way easier to use, more maintainable, and safely handles special characters and spaces in the YAML data. It will also enable other features, such as the rpm-ostree improvement coming in the next commit.
The function name is `get_yaml_array()` because it literally reads it into a Bash array, by the way. Don't change the function name in the future. We may need other functions to read values into strings, etc.
Lowercase, run-on sentences are a nightmare to expand later, because the lack of sentence structure means you can't just add more lines and have a nice flow anymore.
Let's add some punctuation and grammar.
* fix: prevent /etc/ merge issues
discussed at length in #28
also including tons of comments about the issue
* fix: change references of /etc/ to /usr/etc
