model.js: readPropery: handle null sources
model.js: Appending to an array is push() not append()
model.js: Model.fromObject: fix check for prop type is function

And only set the prop if value !== null
Merge pull request #57 from gicmo/modelFixes

Small fixes to model.js

Thanks, LGTM
Application: end point submission takes now an id
models.js: fix small bug in Model constructor
editor.js: first draft of save method (still with errors)