Implement new clinical objects

[jtarraga]

In order to improve the clinical support in OpenCGA, new clinical objects should be created. These objects are:

class ClinicalAnalyst {
   id
   name
   email
   assignedBy
   date
}

class ClinicalAudit {
   author
   Enum action: create, create_interpretation, update, update_interpreattion, ...
   message
   date
}

class ClinicalComment {
   author
   message
   List<String> tags
   date
}