This patch makes configurable the oai_dc crosswalk so to make possible to hide some metadata without hardcoding.
The configuration is read from a new oaidc.properties file in the config dir with the follow syntax:
<schema>.<element>(.<qualifier|*>) = OAI_DC ELEMENT
dc.title = title
dc.contributor.author(CONVERTER) = creator
dc.contributor.editor(CONVERTER) = contributor
where the CONVERTER is the name of an option named plugin (interface class: org.dspace.content.crosswalk.IConverter) that manipulate the string value
A default configuration, with the same behaviour of the "old" OAI_DC crosswalk, is provided