Update compareProjectFiles with regards to the new sync API

[tomasMizera]

MerginApi::compareProjectFiles method needs to be updated to work with the new delta project endpoint.

Outcome:

• compareProjectFiles handles server limits (max # of files and max file size) for v1 sync API
• syncing more than 100 files at once will generate multiple versions, not one
• there is a new, autotested, comparison for delta endpoints and selective sync for v2 API (nothing for manual testing)
• selective sync must work as before