Add two snippets

* `number.html` for form fields that require a number value
* `file_size.html` to display resource sizes in a human friendly way

ckanext/scheming/templates/scheming/display_snippets/file_size.html

@@ -0,0 +1 @@
+{{ h.localised_filesize(data[field.field_name]) }}

ckanext/scheming/templates/scheming/form_snippets/number.html

@@ -0,0 +1,16 @@
+{% import 'macros/form.html' as form %}
+{% call form.input(
+    field.field_name,
+    id='field-' + field.field_name,
+    label=h.scheming_language_text(field.label),
+    placeholder=h.scheming_language_text(field.form_placeholder),
+    type='number',
+    value=data.get(field.field_name),
+    error=errors[field.field_name],
+    classes=field.classes if 'classes' in field else ['control-medium'],
+    attrs=dict({"class": "form-control"}, **(field.get('form_attrs', {}))),
+    is_required=h.scheming_field_required(field)
+    )
+%}
+    {%- snippet 'scheming/form_snippets/help_text.html', field=field -%}
+{% endcall %}