Reset the PING cache on COLLECTION_ERR_FOLDERSYNC_REQUIRED too.

Otherwise some clients will NEVER figure out the hierarchy changed.
Fix phpdoc.
ws
Clarify the meaning of these values.
Hotfix for a chicken/egg problem when renaming a folder.

We need to add the new name to the tempMap so that when we request
the folder object for the renamed folder in order to update it's
state/cache data, we don't generate a new UUID for it as well.

This will be overhauled in 3.0.
Update the serverid in the the collection data when updating the hierarchy.
Specify we want to update the folder's state data as well.
Fix nasty little typo.