Feature Request - Simple javascript toast notifications

[patricklindsay]

Currently Integral uses a (very out of date) version of Toastr to provide an API for developers to display toast notifications. This should be abstracted behind a Integral.Toast namespace and public API so that if the implementation is updated consumers won't need to update their usage.

When doing this we should also remove usage of the no longer maintained toastr-rails gem and pull in the latest toastr version to the asset pipeline.

Lets also make the notifications dismissible.

https://github.com/CodeSeven/toastr
https://github.com/tylergannon/toastr-rails