support browsing genre stations

[sspiff]

With mysb, one can (could) browse P's collection of genre stations from the top of the P app.

[keithpleas]

I mentioned in #13 that you can Search, Created (and Delete) stations in Pandora (web, app) - it just takes a while to propagate to Pyrrha (versus pretty quick in the obsolete Pandora plugin). I'll create a new issue about forced "syncing".

[nabertrand]

I've got the start of genre browsing added in https://github.com/nabertrand/lms-plugin-pyrrha/tree/createstation. I still need to add the bits that creates the station and starts playing it but will hopefully have some time to continue working on it soon.