Use a dedicated logger channel in PuzzleController (uses "php")

@jurgenhaas: I assigned you for a second to let you know, but of course you don't have to fix this. Can be done by anyone who has the time. These infos are filling up our logs and the unclear categorization makes it harder to find real php errors ;)

Done. I don't think we need tests for this.

Great work, thanks for the quick fix!

Automatically closed - issue fixed for 2 weeks with no activity.