L.Draw.Polyline has no more _onClick method

This targets the last stable version (0.2.3)
See https://github.com/Leaflet/Leaflet.draw/commit/8fa143262084e819128e478cd447b177e37d2e7e
Merge pull request #9 from yohanboniface/nomoreonclick

L.Draw.Polyline has no more _onClick method