update xds-server package in docker

scripts/package-update: bash scripts to update xds-server package in docker
monitor updates: default time is 24h, a update is tried at startup
api/v1: 2 new requests:
    - get(updates): return various information about xds-server packages
    - post(updates): update xds-server packages

Change-Id: I1673f7860e57cfe1d4abe5a24609ee46a90b67d8
Signed-off-by: Clément Bénier <clement.benier@iot.bzh>