[BISERVER-12298] An invalid call to UnifiedRepository leads to exception
Merge pull request #2155 from akhayrutdinov/BISERVER-12298

[BISERVER-12298] An invalid call to UnifiedRepository leads to exception
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.
[BISERVER-12093] - Cannot delete invalid Data Source - the check for mondrian schema file was deleted because we can't suppose that it is a valid xml file. Also was changed processing mondrian catalogs in method "loadCatalogsIntoCache".