Better description for Floating IPs quota usage diagram

The overview page in the dashboard has a floating ips resource
diagram showing how many ips are allocated vs. the total amount
allowed by quota. Nevertheless it describes the allocated IPs as
'Used' which makes the User to confuse them with the IPs which are
allocated and both associated with VMs (i.e. used by those VMs).
The diagram description has now been worded "Allocated N of M"
instead of "Used N of M".

Change-Id: If17f902487ea048507a68b030f9884b1affba65f
Closes-Bug: 1394267

horizon/templates/horizon/common/_limit_summary.html

@@ -26,7 +26,7 @@ <h3 class="quota-heading">{% trans "Limit Summary" %}</h3>
     <div class="d3_quota_bar">
       <div class="d3_pie_chart_usage" data-used="{% widthratio usage.limits.totalFloatingIpsUsed usage.limits.maxTotalFloatingIps 100 %}"></div>
       <strong>{% trans "Floating IPs" %} <br />
-        {% blocktrans with used=usage.limits.totalFloatingIpsUsed|intcomma available=usage.limits.maxTotalFloatingIps|quotainf|intcomma %}Used <span> {{ used }} </span> of <span> {{ available }} </span>{% endblocktrans %}
+        {% blocktrans with used=usage.limits.totalFloatingIpsUsed|intcomma available=usage.limits.maxTotalFloatingIps|quotainf|intcomma %}Allocated <span> {{ used }} </span> of <span> {{ available }} </span>{% endblocktrans %}
       </strong>
     </div>