Add option-passing to formatters
Handle turtle
Update instructions re turtle
Merge branch 'master' into author_answers

Conflicts:
	data/fileformats/reactions/formats/format_rdf.py
Fix tests for formatter optionality
Merge branch 'master' into author_answers
Default xml test to using lxml.builder
Merge branch 'master' into author_answers
Roundtrip rdf in both xml and turtle
Merge branch 'master' into author_answers
Turtle example stub
Merge branch 'master' into author_answers
Cleaner to specify species type and label once
Populate turtle example by saving from csv
Clean up node labels in turtle