Fix #242, Fix #497, Fix #574, more metadata support

[dgarijo]

This update addresses the following:

• editorialNote is not added in guides
• Guidelines add which is the preferred metadata for each, and include examples (Fix #242)
• Added dce and dct as elements and terms for dublin core.
• Added:
  • pav:version (http://purl.org/pav/version) (versionInfo)
  • http://purl.org/dc/terms/hasVersion (versionInfo)
  • http://purl.org/pav/lastUpdatedOn (modified)
  • http://www.w3.org/2007/05/powder-s#describedBy (source)
• Added support for logos and guidelines (Fix #497)
• Fix error: when saving properties, there are some nulls in publisher.
• Added support for mod:status.
• Added support for describedby (source)
• Add editorialNote in metadata guide (#592)
• Add source in Widoco (ontology level). And load/save in properties. And form. And HTML.
• Add seeAlso in Widoco (ontology level). And load/save in properties. And form. And HTML.
• Explain how to run from code (Fix #574)