BACKLOG-1581 -- Document interfaces mentioned in MT doc

What was done:
1) added \ changed comments based on DOC team feedback
[BACKLOG-872] Restructure Data Access to allow for deterministic build
Merge pull request #2164 from mdamour1976/cleanup

[BACKLOG-872] Restructure Data Access to allow for deterministic build
Merge pull request #2160 from kolinus/BACKLOG-1581

BACKLOG-1581 -- Document interfaces mentioned in MT doc
[BACKLOG-872] Fixes due to the introduction of the Property type in
metadata.
Merge pull request #2168 from e-cuellar/master

[BACKLOG-872] Fixes due to the introduction of the Property type in metadata.
BACKLOG-1178: Document File Management for the DI Server

There are jMeter tests for DI server: Document File Management, User Roles etc.