WIP : allow for entering rendering parameters prior to PDF generation
merge
#36 : display list of existing generations when setting up rendering
#36 : update links towards 'setup_rendering'
Restore 'clean' step in generation'
Traitement des options 'papersize' et 'orientation'
Use songbook.title, .description and .author for PDF generation; this fields can no more be customized in Task.
Correct display of generated songbooks
Display paper size and orientation in PDFs list
Reorganize get_as_json methods and cals
Merge branch 'master' of https://github.com/jmclem/songbook-web into jmclem-master

Conflicts:
	generator/management/commands/importsongs.py
Merge branch 'jmclem-master'