[NEXUS-3742] Add grace days after release on snapshot remover

Signed-off-by: Alin Dreghiciu <adreghiciu@gmail.com>
[NEXUS-3742] Drop unwanted log

Signed-off-by: Alin Dreghiciu <adreghiciu@gmail.com>
Merge remote-tracking branch 'origin/master' into nexus-3742-grace-on-remove-snapshots
Merge pull request #823 from sonatype/nexus-3742-grace-on-remove-snapshots

REVIEW: [NEXUS-3742] Add grace days after release on snapshot remover