mpd: List browse results before playlists in lsinfo

This makes directories from extensions appear before playlists in the
result of the lsinfo command, which is desirable in clients that does
not sort the result.
mpd: Test order of result from lsinfo
Merge pull request #755 from trygveaa/feature/lsinfo-change-order

mpd: List browse results before playlists in lsinfo