- Bump version: 9.17.7 → 9.17.8

- Make result compression in the bundler optional

Calling kiwi result bundle will take the image build results
and bundle the relevant image files according to their image
type. Depending on the result configuration this could instruct
the bundler to compress one or more files from the result.
By default this compression is switched off in the bundler but
can be activated to save storage space and speedup download
of the image with the following runtime configuration:

bundle:
- compress: true|false

If compression is activated the result image has to be
uncompressed before it can be used. This Fixes #901