Add brand headings

src/templates/converse_brand_heading.html

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+<div class="brand-heading">
+    <i class="icon-conversejs"></i>
+    <span class="brand-name">converse</span>
+</div>

src/templates/inverse_brand_heading.html

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+<span>
+    <h1 class="brand-heading"><i class="icon-conversejs"></i>inverse</h1>
+    <p class="brand-subtitle"><a href="https://conversejs.org">Open Source</a> XMPP chat client</p>
+</span>