[CDA-81] Multi-tenancy does not work with CDA cache enabled
 - added functionality: ability to define CDA cache keys for each dataAccess

<DataAccess>
	<Cache enabled="true" duration="500">
    		<Key name="tenantId" value="${[session:org.pentaho.tenantId]}" default="/pentaho/tenant0"/>
	</Cache>
</DataAccess>
Merge pull request #52 from pedrofvteixeira/CDA-81

[CDA-81] Multi-tenancy does not work with CDA cache enabled