[FIX] res_config: Fix several layout issues on config views

- subscription settings are broken and show up at the bottom of any setting page: https://drive.google.com/a/odoo.com/file/d/0B1uIL9E_zXrra01leUZ1Wnczbms/view?usp=drivesdk
- don't put setting item of the app you are configuring at the top of the list: https://drive.google.com/a/odoo.com/file/d/0B1uIL9E_zXrrdXEwUmFWTTlLd1E/view?usp=drivesdk
- hide empty sections when searching not in debug mode: https://drive.google.com/a/odoo.com/file/d/0B1uIL9E_zXrrVGFOa0FKVmtNTWs/view?usp=drivesdk
- when installing Invoicing, setting item should be Invoicing and not "Accounting": https://drive.google.com/a/odoo.com/file/d/0B1uIL9E_zXrrWGQwY1ktaXlNSUk/view?usp=drivesdk
- app labels: https://drive.google.com/a/odoo.com/file/d/0B1uIL9E_zXrreXlNTXZnbU13aFk/view?usp=drivesdk
- coupon programs links: duplicate in sales + no link at all in website: https://drive.google.com/a/odoo.com/file/d/0B1uIL9E_zXrraTV1YTNPdWU2VUE/view?usp=drivesdk
- delivery methods: links are duplicated in sales settings https://drive.google.com/a/odoo.com/file/d/0B1uIL9E_zXrrczR5X1FOUllUZHM/view?usp=drivesdk
- add subtitles to all the carriers in sales settings: https://drive.google.com/a/odoo.com/file/d/0B1uIL9E_zXrrS1NXXzhwRTFQV2c/view?usp=drivesdk
- inner options should never be in bold:
        customer account: https://drive.google.com/a/odoo.com/file/d/0B1uIL9E_zXrrMnpualBta2x6dU0/view?usp=drivesdk
        phone validation: https://drive.google.com/a/odoo.com/file/d/0B1uIL9E_zXrraHJrYngtaGJ6T2s/view?usp=drivesdk
        signature & payment: https://drive.google.com/a/odoo.com/file/d/0B1uIL9E_zXrrWTJ3dVBuTzNONlU/view?usp=drivesdk
        bill control: https://drive.google.com/a/odoo.com/file/d/0B1uIL9E_zXrrRy16UkdTWWdrdDQ/view?usp=drivesdk
- make similar settings look the same through all the apps:
        taxcloud: https://drive.google.com/a/odoo.com/file/d/0B1uIL9E_zXrraGlVWmNXRjJ5WEk/view?usp=drivesdk
        pricelist: https://drive.google.com/a/odoo.com/file/d/0B1uIL9E_zXrrQ2pwVmtEZXM1SWM/view?usp=drivesdk
        multi-currencies: https://drive.google.com/a/odoo.com/file/d/0B1uIL9E_zXrrTFNWTTJpcS1XbnM/view?usp=drivesdk
        shipping costs: https://drive.google.com/a/odoo.com/file/d/0B1uIL9E_zXrrM2hKdk5XRy1WTjg/view?usp=drivesdk

views/res_config_settings_views.xml

@@ -6,7 +6,7 @@
         <field name="model">res.config.settings</field>
         <field name="inherit_id" ref="website.res_config_settings_view_form"/>
         <field name="arch" type="xml">
-            <xpath expr="//div[@id='sale_coupon']" position="after">
+            <xpath expr="//div[@id='website_sale_coupon']" position="after">
                 <div class="content-group">
                     <div class="mt16" attrs="{'invisible': [('module_sale_coupon', '=', False)]}">
                         <button name="%(sale_coupon.sale_coupon_program_action_promo_program)d" icon="fa-arrow-right" type="action" string="Promotion Programs" class="btn-link"/>