Merge pull request #848 from Kienz/patch-1

Move `setColor` from `fabric.Text` to `fabric.Object`
Few contribution tweaks
Alias "jpg" format to "jpeg". Closes #806
Avoid creation of `exports` global var as this messes up QUnit (and probably something else)
Fixed `object.toDataURL` if object's originX/originY != 'center'
Add documentation to object.toDataURL for options object
Alias "jpg" format to "jpeg". Closes #806