added missing annotation driver class. small refactorings. added first ClassMetadata serialization tests.

Fixed paths that were referring wrong namespace resolution.
Implemented more Parser and AST classes: JoinVariableDeclaration and Join.
Fixed wrong semantical checks of IndexBy grammar rule. They should be in IdentificationVariableDeclaration and JoinVariableDeclaration.

Fixed wrong DQL in IdentifierRecognitionTest.php

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