clean up preset examples
a better way for DATABASE_URL
documentation improvements
you cannot install twill using pip -- cmon guys
syncdb must also use correct preset
database settings from URL override others
Merge branch 'make_presets_neater' into eHealth_staging

Conflicts:
	.gitignore
	formhub/preset/default_settings.py
	formhub/preset/production_example.py
	formhub/preset/url_db.py