T020: basic support for (typed) tags

[menzowindhouwer]

Add support for tagging objects. Basic data model:

Object(oid,...) --< tags(oid,tid) >-- Tag(tid,name,type,owner?)

So an Object can have multiple tags, a Tag can be associated with multiple objects. A Tag has a type. Types can be:

• specific (in general created and maintained by the system, i.e., immutable for users), e.g., status, time, path, ...
• or generic, i.e., user (created and maintained by the user)

Examples (open for discussion):

• time:2018 October 3 9:45
• time:2018 October 3
• time:2018 October
• time:2018
• path:myFiles/2018/video
• path:myFiles/2018
• dir:myFiles
• dir:2018
• dir:video
• user:My Project XYZ
• user:to validate

Discussion: the upload path could also function as suggestions for user tags, in which case path and dir aren't needed.

Using a view the object info obtained via DreamFactory can contain the actual tags.

For search the tags should also be in the SOLR.

Find the right place in the workflow to instantiate the tags to be created by the system.

[BasLee]

Tags can be created Automatic system tags are generated

TODO: Add tags to solr Allow users to filter files in UI by tag