add folder structure for external sftp upload
Merge remote-tracking branch 'upstream/develop' into PLFM-3019

Conflicts:
	services/repository-managers/src/main/java/org/sagebionetworks/repo/manager/file/FileHandleManagerImpl.java
Merge pull request #1544 from marcel-blonk/PLFM-3019

add folder structure for external sftp upload