Saved tools on the profile page

Feature to show the tools that the current user has saved data for, and if there are none, to show a simple message prompting the user to try a tool.

There are some issues here, in particular having to use Warden in test mode so that a method on the user object can be stubbed. Also, this does represent a list of tools in the same way recommended tools also is a list of tools. Seeing this unified at some point would be a good idea.

Thoughts?
@benlovell `#has_tool_data` methods should be implemented on the `User` model for each engine that supports saved data. It's also why I used `if respond_to?` to check first if the method doest exist for the specified tool or not.