This performs a lot of bugfixing and general cleanup to the
Fedora/CentOS builds, including moving the create_tarball into the
docker-build.sh script, remove some old long versions from the spec
file, correcting several bugs with the Docker environment including
splitting them into more discrete layers, and finally making sure
jellyfin-web is included properly in the RPM.
1. Update README.md to remove some old info
2. Remove common.build.sh from all the build scripts
3. Remove common.build.sh script
4. Remove the docker folder as this isn't used at all
