add a number field

The field has three option :

- lesser or equal than. If null, this option is ignored ;
- greather or equal than. If null, this options is ignored ;
- precision : the number of decimal after the number ;
- text after the field : a text to show after the field.

The field is rendered as an HTML integer input if precision = 0, or a
symfony number field if precision > 0.

ref chill-project/Chill-CustomFields#11

Tests/Fixtures/App/app/config/config.yml

@@ -66,7 +66,7 @@ security:
             anonymous: ~
             form_login:
                 csrf_parameter: _csrf_token
-                intention: authenticate
+                csrf_token_id: authenticate
                 csrf_provider: form.csrf_provider
             logout: ~
     access_control: