Allow to create disseminations and present them in browse

[luis100]

• A dissemination can be created by a plugin based on an AIP or a representation.
• A dissemination can be just a link to an outside resource (e.g. the database viewer), but it must be created by a plugin that will ingest it to the database viewer.
• A dissemination can also have resources, e.g. a JPEG version of an uncompressed TIFF representation.
• The list of disseminations can appear below the representations
• The disseminations will always be services that can be called by external systems (they are integration points)

@jmaferreira please review the description this solution

[jmaferreira]

We should be compatible with this spec:
http://www.eark-project.com/resources/project-deliverables/61-d53-pilot-dip-specification/file

The ability to produce E-ARK DIPs will replace our second pilot in EARK. The DIP must be compatible with the IP viewer that Magenta is developing.

[luis100]

Presenting DIPs in files.