fix #334 ('include' places a "null" element to the result if no data is related)
reuse existing DAO.identifiers
fixes #204 thanks to @bpartridge
use native array method
Merge branch 'hasManyFix' of git://github.com/innofluence/sequelize into innofluence-hasManyFix
#449
Merge branch 'master' of git://github.com/guersam/sequelize into guersam-master
re-run
test
test
construct postgresql array from js array
use Array.isArray and fix if-block style