make audiotracks filterable by specific tags

[hburgund]

In other words, allow the ability to restrict an audiotrack to playing only assets that have a certain tag or set of tags. Lots of aesthetic possibilities for things like adjusting the frequency of field recording assets in relation to spoken assets. This would arguably be particularly useful for non-geo-listen projects, but I think it would be useful all-around as well.

Server Requirements

• add new optional ManyToManyField called audiotrack.tag_filters
• update admin to handle new field
• update all api/2/audiotracks/ requests accordingly
• update documentation

[13rac1]

Audio Track 1: People's thoughts
Audio Track 2: Rain/Thunder
Audio Track 3: Birds and other animals

I'd like this.

[hburgund]

Yes! And when we have the ability to have different ranges/zones for each asset (rather than just the simplistic asset center and project-level radius), then we can really start doing some awesome aesthetic stuff!

[hburgund]

Now that we are finally moving towards client-side mixing, the only work that needs to be done on the server is adding the audiotrack.tag_filters stuff.

The actual filtering mechanism will be built in roundware-ios-framework-v2, so I will handle that there.

[hburgund]

fixed by #372