Clean up uid/randomid/guid changes.

Clean up uid/randomid/guid changes.

Use Horde_Support_Randomid:: for local object ids when we need a smaller value,
Use Horde_Support_Guid:: for object uids (not Horde_Support_Uuid:: since these need
to be globally unique).
Use Horde_Support_Uuid for share ids and other cases where we can use a larger value.

I still question the need for even the Randomid in places like internal object ids, when
integer autoincrement fields would suffice.