Multilevel dojo-props support

Bug
---
Before this commit, ```data-dojo-props="constraints:{min:0}"``` doesn't work as
the current implementation support only one depth level of property.

Fix
---

We now use the eval function for the dojo-props attribute.
After this commit, the dojo-props must respect a valid form (as in vanilla dojo).

Eg:
	```	<select
		   		data-dojo-widget="dijit/form/FilteringSelect"
		   		data-dojo-props="name: 'filterSelect'; searchAttr: search">```

	now becomes:

	```	<select
		   		data-dojo-widget="dijit/form/FilteringSelect"
		   		data-dojo-props="name: 'filterSelect', searchAttr: 'search'">```
Fix for dijit/form/Select and dijit/form/FilteringSelect

When using those widget, it's better to use the item field instead of value
to fit the angularjs way of doing things.

Like that, the select returns the full object in the model and not the just the id.

Now when the model changes, the dojo widget is also updated automatically.
Merge pull request #7 from amaury-d/master

Multi levels prop support and fixes for dijit/form/FilteringSelect and dijit/form/Select