Set an actual User-Agent

I’m aware of the discussion in #53 (closed). However, I want to argue that the solution was wrong. I’d like to introduce a unique fingerprint with GNOME Podcasts-branding instead. Here are my reasons:

• The core issue in #53 (closed) was the lack of a User-Agent, and not browser-sniffing per say. Podcast clients has all sorts of unique User-Agents. The lack of any User-Agent header triggered a mod_security rule, which lead to the specific issue.
• There is no need to increment the version number in the User-Agent unless feed parsing changes significantly.
• Podcasters see their listeners using a Linux product and not a generic Windows browser. This is good for the Linux desktop ecosystem.
• Free advertisement for the product. May get mentioned on shows when podcasters see a new client appear in their analytics.
• Podcasters gets to more accurately measure listenership (client-reputation); this has consequences for their ad partners and finances.
• Please don’t attempt to fake Firefox’s User-Agent. GNOME Podcasts’ whole HTTP fingerprint (all headers, their content, and even their order) is unique anyway. There are also other ways to fingerprint feed readers without relying on the User-Agent or cookies. There is no real privacy gain to be had here.

Why “Hammond”? No Reason. Could use “GNOME-Podcasts” instead but it looks weird and I imagine that it may trigger partial matches against the “podcast” substring in some environments and log anlysis programs.