Add initial support for updating the Directory Server schema over protocol.  In
particular, this commit makes it possible to add new attribute types and
objectclasses and have them written to the 99-user.ldif file.  This
implementation does not yet support interacting with any other schema element
types, removing or replacing existing schema elements, or interacting with any
files other than 99-user.ldif.  Additional functionality will be added in the
future to enable these capabilities.

OpenDS Issue Number:  366