Add song: Daniel Balavoine - Aimer est plus fort que d'être aimé
Add song: Daniel Balavoine - L'aziza
Add song: Francis Cabrel - Encore et encore
Add song: Francis Cabrel - Sarbacane
Add song: Maxime Le Forestier - Né quelque part
Add song: Jacques Dutronc - L'opportuniste
Remove songs directory as it now belongs to its own repository

See http://github.com/crep4ever/songbook-data
Update readme
Merge branch 'master' into next

Conflicts:
	readme.md
	songbook_core/data/examples/songs/chevaliers_de_la_table_ronde.sg
	songbook_core/data/examples/songs/greensleeves.sg
	songbook_core/data/examples/songs/traditionnel.jpg
	songbook_core/data/examples/songs/vent_frais.sg