Add MiqWidget importing/exporting

Related to Bugzilla 1115106
https://bugzilla.redhat.com/show_bug.cgi?id=1115106

@gmcculloug @dclarizio @h-kataria Please Review.

Also note that the styling for the slick grid stuff is off, but I figured that could be fixed after this is in.
Actually since you're reading the same parameter in the else, you can do

```ruby
upload_file = params.fetch_path(:upload, :file)
if upload_file.nil?
else
  blah blah (upload_file)
end
```