Add Associations ABCD mapping

[muttcg]

Show occurrence associations

This ABCD record contains a link to another occurrence.
It would be great to show these occurrence relations

<UnitAssociation>
	<AssociatedUnitSourceInstitutionCode>SNSB-JME</AssociatedUnitSourceInstitutionCode>
	<AssociatedUnitSourceName>JMEpiscescoll</AssociatedUnitSourceName>
	<AssociatedUnitID>JME-ETT-03930 / 726794 / 374459</AssociatedUnitID>
	<AssociationType language="en">Predator/Food</AssociationType>
	<Comment language="en">http://biocase.snsb.info/wrapper/pywrapper.cgi?dsa=JMEpiscescoll</Comment>
</UnitAssociation>

Associations: gbif/portal-feedback#439