* Refuse to serve icons from urls

Rancher now gives the link to the user directly for the user to load.
There is no need for Rancher to host externally available images.

* Remove helm fetch icon logic

* Return the icon url to the template to display in the UI

Problem: The icon url was not returned to the template so the template
would not display icons for charts with remote icons.

Solution: Do not fetch the icon but still return the url of the icon
to the template.