CORE-4954 Fixed DiskResourceUtil#isDescendantOfFolder

Added a trailing slash to the ancestor path used to check against the potential descendant.
This prevents false positives for folders like "/home/test" and "/home/test 1".
CORE-4806: Massive refactor of App editor code
core-4780 fix file size calculation logic
Merge branch 'master' into STABLE
Versioned as part of Release Candidate for v1.8.4