Updated all API calls with ServerDownException.
Updated the error code for 504.
Merge remote-tracking branch 'upstream/dev-branch' into dev-branch

* upstream/dev-branch:
  Fixed issue with editing the folder title.
  "Implemented additional changes for Add suggestions in collection edit under search"
  DO-4843, DO-4702 Bugs has been fixed.
  Fixed In FF browser ,under tags the default resource images is broken.
Merge pull request #711 from anilgooru/dev-branch

Bug fixes.