dashboard: check if vm has agent installed for pw reset

circle/dashboard/templates/dashboard/vm-detail.html

@@ -121,7 +121,14 @@
         <dd style="font-size: 10px; text-align: right; padding-top: 8px;">
           <div id="vm-details-pw-reset">
           {% with op=op.password_reset %}{% if op %}
-          <a href="{% if op.disabled %}#{% else %}{{op.get_url}}{% endif %}" class="operation operation-{{op.op}}" data-disabled="{% if op.disabled %}true" title="{% trans "Start the VM to change the password." %}"{% else %}false" {% endif %}>{% trans "Generate new password!" %}</a>
+          <a href="{% if op.disabled %}#{% else %}{{op.get_url}}{% endif %}"
+            class="operation operation-{{op.op}}"
+            {% if op.disabled %}
+            data-disabled="true"
+            title="{% if instance.has_agent %}{% trans "Start the VM to change the password." %}{% else %}{% trans "This machine has no agent installed." %}{% endif %}"
+            {% endif %}>
+            {% trans "Generate new password!" %}
+          </a>
           {% endif %}{% endwith %}
           </div>
         </dd>