Improvements to Metadata, AD User Import and Bug Fixing

SD-945, SD-1051, SD-668

There were some repetitive attributes in metadata_schema.
Added behave tests for testing metadata.
Agreed. But if we don't have this here this field doesn't make an entry into archive_versions collection. That's the reason this field is moved from archive_media to metadata_schema and validation is being done manually in ArchiveMediaService.