added edge id back to edge model, refactored drawNodes to mirror drawEdges and reimplemented remove behavior and added delete and backspace key funcitonality
refining force layout
Merge pull request #283 from ifjorissen/v0.2

V0.2
Merge branch 'v0.2' of https://github.com/GraphAlchemist/Alchemy into filters

Conflicts:
	app/scripts/alchemy/drawing/drawEdges.coffee
Edge model tests -- edge.source.id not edge.source