Use number_field for Field::Number

Created by: rkbhochalya

It would be nice to use number_field helper to render input field in the form partial view for Field::Number fields. You are using text_field at the moment.

<%#
# Number Form Partial

This partial renders an input element for number attributes.
By default, the input is a text field.

## Local variables:

- `f`:
  A Rails form generator, used to help create the appropriate input fields.
- `field`:
  An instance of [Administrate::Field::Number][1].
  A wrapper around the number pulled from the database.

[1]: http://www.rubydoc.info/gems/administrate/Administrate/Field/Number
%>

<div class="field-unit__label">
  <%= f.label field.attribute %>
</div>
<div class="field-unit__field">
  <%= f.text_field field.attribute %>
</div>