Fix OPENDJ-1361 : Matching Rules and Syntaxes have a reference to a schema 
that can be changed, leading to unexpected behavior

* Duplicate syntaxes and matching rules when they are taken from 
 another schema
* Add new methods buildSyntax() and buildMatchingRule() to allow addition
 without lazy initialization
* Add new method isValidated() to check if a syntax or a matching rule
 has been validated
* Remove workarounds from unit tests