* Allowing for templated urls in iFrame
This can allow for passing {{ width }} and {{ height }} as dynamic
attributes in the iFrame's URL.
The new method Slice.render_template method could do more eventually
exposing more variables to be used in dynamic strings.
* Passing function references
* js linting
* Periodically update the slices in the dashboard
* Make the refresh interval changeable
* Add the button and the modal for the user to change the refresh interval
* Don't use callback for refreshing
* Randomize to prevent all widgets refreshing at the same time
* Show the loading icon as an overlay when the slices refresh
* Move window.alert() calls to bootstrap modals. Also log errors that occur to console.
* move misc modal to basic template so it's available on all pages.
