[IMP] website_blog: replace images and add xml ids

* Replace demo blog post covers
* Add xml ID to demo images so they can be easily replaced by themes
* Remove unused images

addons/website_blog/data/website_blog_data.xml

@@ -15,46 +15,21 @@
 
         <!-- Pre loaded covers -->
 
-        <record model="ir.attachment">
-            <field name="name">Chain</field>
-            <field name="datas_fname">chain.jpg</field>
+        <record id="website.blog_post_cover_01" model="ir.attachment">
+            <field name="name">Blog Post Cover 1</field>
+            <field name="datas_fname">Blog Post Cover 1</field>
             <field name="res_model">ir.ui.view</field>
             <field name="type">url</field>
-            <field name="url">/website_blog/static/src/img/library/chain.jpg</field>
+            <field name="url">/website_blog/static/src/img/demo/blog_post_cover_1.jpg</field>
         </record>
 
-        <record model="ir.attachment">
-            <field name="name">Wood Wall Texture</field>
-            <field name="datas_fname">woodtexture.jpg</field>
+        <record id="website.blog_post_cover_02" model="ir.attachment">
+            <field name="name">Blog Post Cover 2</field>
+            <field name="datas_fname">Blog Post Cover 2</field>
             <field name="res_model">ir.ui.view</field>
             <field name="type">url</field>
-            <field name="url">/website_blog/static/src/img/library/woodtexture.jpg</field>
+            <field name="url">/website_blog/static/src/img/demo/blog_post_cover_2.jpg</field>
         </record>
-
-        <record model="ir.attachment">
-            <field name="name">Gauze Green Texture</field>
-            <field name="datas_fname">gauze-green-texture.jpg</field>
-            <field name="res_model">ir.ui.view</field>
-            <field name="type">url</field>
-            <field name="url">/website_blog/static/src/img/library/gauze-green-texture.jpg</field>
-        </record>
-
-        <record model="ir.attachment">
-            <field name="name">Special Flower Texture</field>
-            <field name="datas_fname">flower_texture.jpg</field>
-            <field name="res_model">ir.ui.view</field>
-            <field name="type">url</field>
-            <field name="url">/website_blog/static/src/img/library/flower_texture.jpg</field>
-        </record>
-
-        <record model="ir.attachment">
-            <field name="name">Sad Danbo</field>
-            <field name="datas_fname">sad_danbo.jpg</field>
-            <field name="res_model">ir.ui.view</field>
-            <field name="type">url</field>
-            <field name="url">/website_blog/static/src/img/library/sad_danbo.jpg</field>
-        </record>
-
     </data>
 
     <data>

addons/website_blog/data/website_blog_demo.xml

@@ -19,7 +19,7 @@
             <field name="published_date" eval="time.strftime('%Y-%m-%d %H:%M:%S')"/>
             <field name="website_meta_keywords">Odoo, email</field>
             <field name="website_meta_description">The Future of Emails</field>
-            <field name="cover_properties">{"background-image": "url(/website_blog/static/src/img/library/flower_texture.jpg)", "background-color": "oe_yellow" ,"opacity": "0.6", "resize_class": "cover container cover_narrow"}</field>
+            <field name="cover_properties">{"background-image": "url(/web/image/website.blog_post_cover_01)", "resize_class": "cover container cover_narrow"}</field>
             <field name="content"><![CDATA[
 <section class="s_text_block">
     <div class="container">
@@ -133,7 +133,7 @@
             <field name="website_published" eval="True"/>
             <field name="published_date" eval="time.strftime('%Y-%m-%d %H:%M:%S')"/>
             <field name="tag_ids" eval="[(6, 0, [ref('blog_tag_1'), ref('blog_tag_2')])]"/>
-            <field name="cover_properties">{"background-image": "url(/website/static/src/img/library/ship_sea.jpg)", "background-color": "oe_green" ,"opacity": "0.6", "resize_class": "cover container-fluid cover_full"}</field>
+            <field name="cover_properties">{"background-image": "url(/web/image/website.blog_post_cover_02)", "resize_class": "cover container-fluid cover_full"}</field>
             <field name="content"><![CDATA[
 <section class="s_image_text">
     <div class="container">