HV-819 Unrelated comment fixes
HV-819 Simplifying AnnotationMetaDataProviderTest
HV-819 Establishing @UnwrapValidatedValue annotation for marking validated elements which need to be unwrapped prior to validation

* Providing annotation
* Extending raw and aggregated models with "requiresUnwrapping" attribute
* Extending annotation meta data provider to populate that property
HV-819 Adding ValidationValueUnwrapper SPI and API for registering unwrapper implementations

* Adding addValidationValueUnwrapper() to HibernateValidatorConfiguration and HibernateValidatorContext
* Passing list of unwrappers into ValidatorFactory and Validator
HV-819 Unwrapping validated elements if marked with @UnwrapValidatedValue and matching processor is present
HV-819 Using shared instance of TypeResolver
HV-819 Adding unwrapValue() option to constraint API
HV-819 Using more generic name "validated value handler" for type and member names

* Renaming API/SPI packages, types and members
* Adding package-info.java
* Improving documentation, marking API/SPI as experimental
HV-819 Incorporating further review remarks
HV-819 WIP Updating reference guide; Adding new packages to OSGi manifest
HV-645 Unifying ConstraintLocation sub-types into one single class
HV-645 Making sure ElementDescriptor#getType() exposes the complete generic type
HV-645 Getting rid of elementType field in ConstraintLocation
HV-645 Making semantics of ConstraintLocation members more explicit