Merge pull request #304 in ZP/z-push from bugfix/ZP-989-warning-that-readonly-flag-is-undefined to develop

* commit '881fc1f3':
  ZP-989 Output current permission flags on all additional folders in AdditionalFolderList(), criteria to add a shared folder in the ChangesMemoryWrapper should always be on the read only flag, refixed typo in Kopano backend.
  ZP-989 Reverted: "Remove readonly parameter from backends' Setup() function. Check"
  ZP-989 Backward compatibility fixes for old style folder ids.
  ZP-989 Remove readonly parameter from $additionalFolders in config.php and where it was used in the code.
  ZP-989 Remove readonly parameter when adding an additional folder via webservice.
  ZP-989 Remove readonly parameter from backends' Setup() function. Check for only read permission in Kopano backend Setup().