Modify restructure SIP service to account for existing directories and structure

[bonniegee]

This includes:

• identify whether the submissionDocumentation subdirectory in the metadata directory exists before trying to create it
• identify whether the objects directory exists before creating it and moving everything in data to objects

[bonniegee]

Identifying whether directories exist already is likely already covered, but a test needs to be added to confirm this.

[helrond]

Relies on #96