[Fix #398] Add form-select CSS class to select elements

[themowski]

Overview

This PR addresses #398. It integrates the form-select CSS class with various select elements in the form_snippets directory. This causes the select elements to be rendered consistently with other dropdown menus in the CKAN UI.

Changes

• Add form-select to "class" attribute when invoking form.select() macro in form_snippets/select.html and form_snippets/datetime_tz.html
• Add form-select to class on hardcoded select element in form_snippets/organization.html