Added support for annotations in generated APIs.

Added support for annotations in generated APIs.

Added AnnotationType and AnnotationTypeBuilder into binding-model-api;
Modified GeneratedTransferObject -> now extending from GeneratedType -
implementation modified accordingly;
Added getAnnotations property into: Enumeration, GeneratedType,
GeneratedTransferObject and MethodSignature interfaces;
Added addAnnotation method into EnumBuilder, GeneratedPropertyBuilder,
GeneratedTOBuilder, GeneratedTypeBuilder, MethodSignatureBuilder;

Added implementation of AnnotationType into all builder implementations
in binding-generator-impl project part;
Added AnnotationTypeTest into binding-generator-impl;
Package name in src/test/java for binding-generator-impl changed to
org.opendaylight.controller.sal.binding.generator.impl to
test package protected classes;

In binding-java-api-generator CompositeKeyGenerator renamed to
ClassCodeGenerator;
Added implementation to write annotations for interface and class *.java
files;
Added support methods for annotations to Generator Util class;

Signed-off-by: Lukas Sedlak <lsedlak@cisco.com>