[NEXUS-5740] Add option for forcing a full scan of repository while re-generating yum metadata

Signed-off-by: Alin Dreghiciu <adreghiciu@gmail.com>
[NEXUS-5740] Exclude rpm files from directories starting with dot (".") wile scanning

Signed-off-by: Alin Dreghiciu <adreghiciu@gmail.com>
[NEXUS-5740] Add IT verifying that files under dirs starting with dot (".") are not indexed

This will solve problem of indexing rpms from trash folder (.nexus/trash)

Signed-off-by: Alin Dreghiciu <adreghiciu@gmail.com>