Working around lastfm features.

Fixed lastfm workflow with "now playing" and scrobbling feature(Maybe Issue #2672). After scrobble request song was displayed on "just listened" and "listening now", that was wrong. Now listeting request sends after starting song. Scrobble works through cache. Cache send tracks on stop, next, prev, change song events. I think that it is correct algorithm for scrobbling. 
I have a couple ideas to improve working with lastfm. I'll try realize them later.

Changed logic of love track action and fix Issue #3515.

I'll be glad to find my code in my favorite player source code.
Thanks.