server: switch to killbill-skeleton

This also upgrades metrics, jetty and jersey to their latest stable versions.

Signed-off-by: Pierre-Alexandre Meyer <pierre@mouraf.org>
.gitignore: ignore server log files

Signed-off-by: Pierre-Alexandre Meyer <pierre@mouraf.org>
.idea: update configuration for final inspections

Signed-off-by: Pierre-Alexandre Meyer <pierre@mouraf.org>
Merge branch 'master' of github.com:killbill/killbill
server: fix remaining properties

Signed-off-by: Pierre-Alexandre Meyer <pierre@mouraf.org>