RA-1611: Handling of <encounterDiagnoses/> "0" attributes.
* RA-1611 : Follow up commit for diagnosisSets and diagnosisClasses parameters alternate between 'null' and the 'default' from the their GPs
* RA-1611, RA-1610, RA-1603, RA-1599 : Follow up commit to conditionally add attributes to <encounterDiagnosis*/>
* RA-1611 : Allow querying for diagnoses against all provided search parameters
* RA-1611 : When any attribute is specified, all defaults drop
* RA-1611 : Missing diagnosis search parameters to default to using GP defined defaults
* RA-1611 : Specifing null for diagnosisSets and diagnosisConceptSources through '0' char
* RA-1611 : Documenting the usage of '0' for diagnosis search
* RA-1611 : Formating changes on comments and javadoc
