patch: Don't allow to the date to wrap

When rendered on smaller screens, the mininum column size for the date
was reached and the text was wrapping. We can force it to not wrap with
white-space: nowrap; and bootstrap already includes a convenient
text-nowrap class.

Fixes: #44
Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>

patchwork/templates/patchwork/patch-list.html

@@ -156,7 +156,7 @@
 {% for tag in project.tags %}
    {{ patch|patch_tags:tag }}
 {% endfor %}
-   <td>{{ patch.date|date:"Y-m-d" }}</td>
+   <td class="text-nowrap">{{ patch.date|date:"Y-m-d" }}</td>
    <td>{{ patch.submitter|personify:project }}</td>
    <td>{{ patch.delegate.username }}</td>
    <td>{{ patch.state }}</td>