Commit b6eb8dff64 renamed compression
setting environment variables to follow consistent style.
Although it preserved backward compatibility for the most part (i.e. it
handled MINIO_COMPRESS_ALLOW_ENCRYPTION, MINIO_COMPRESS_EXTENSIONS, and
MINIO_COMPRESS_MIME_TYPES), MINIO_COMPRESS_ENABLE was left behind.
Additionally, due to incorrect fallback ordering, and DefaultKVS
containing enable=off allow_encryption=off (so kvs.Get should've been
tried last), that commit broke MINIO_COMPRESS_ALLOW_ENCRYPTION (even
though it appeared to be handled), and even older MINIO_COMPRESS, too.
The legacy MIME types and extensions variables take precedence over both
config and new variables, so they don't need fixing.
This is to ensure that there are no projects
that try to import `minio/minio/pkg` into
their own repo. Any such common packages should
go to `https://github.com/minio/pkg`
