Restores Last.fm service to Amarok with the following changes:
- restore Last.fm's cmake task
- add/replace deprecated defs to enable compilation
- fix authentication (method: auth.getMobileSession) to the current API version. Now it uses HTTPS and use liblastfm's signing function
- remove references to "neighbours" since API method "user.getNeighbours" is deprecated
- remove suggestion to join "Amarok Users" community from configuration dialog since Last.fm no longer have communities