Fix for react addons clasSset deprecated warning

use express.js server for tests; closes #1465

Fixes #1405

Use an express.js server for tests instead of http-server. The primary
reason for this is that express has an available middleware that allows
us to specificy the location of the favicon other than the root
directory. This is needed because the favicon lives in the site-assets
directory.

Backbone: remove unneeded logic in todo View

The removed check is unncecessary and also incorrectly implemented,
resulting in a test failure (the "Editing should trim entered text"
example) and flawed user interaction. This change results in 100%
passing tests and the desired user interaction.

Unneeded: the associated comment states that "Model values changes
consisting of whitespaces only are not causing change to be triggered",
and so the code manually triggers a change event when the only change to
the todo is whitespace being added at the beginning and/or end of the
todo. However, there is no need for the change event when this is the
only change. So the situation described in the comment is not a problem.
The change event triggers a re-rendering of the view, but if the only
change is whitespace at the beginning or end, which is trimmed off,
anyway, then re-rendering is pointless.

Incorrectly implemented: The code in question is
`this.model.trigger('change');`. This ultimately raises an error,
because (perhaps surprisingly) when the 'change' event is manually
triggered on a model, the model is not automatically bound as the so-to-
speak "context" of that change. This can be corrected manually like so:
`this.model.trigger('change', this.model);`. This eliminates the error
and failing test case. However, as this code is not needed, anyway, of
course it's better to simply remove it. :)

⚡️ Automated Leak Detection on CI ⚡️ 

Close #1339

Js_of_ocaml is a compiler of OCaml bytecode to Javascript.
OCaml is a general purpose programming language with an
emphasis on expressiveness and safety. Js_of_ocaml brings
nearly all the OCaml features to Javascript. And especially
its powerful type system.

Update React Readme

TodoMvc example for scalajs-react

Close #1459

Polymer 1.0 demo cleanup

The app is getting outdated and is these days even totally broken sowe
decided to remove it, till someone volunteers to maintain it and PRs it
back with all remaining issues fixed.

There was an open PR with some updates but it went inactive:
https://github.com/tastejs/todomvc/pull/1241

Close #1241
Fix #1222
Ref #1234
Ref #1110

Update index.html

comment was using `todos` whereas the code is using `todos-react-backbone` - i opted for a non-breakable comment instead

🍕🌟Polymer 1.0 🌟🍕

* Update for spec complience
* Polymer 0.5 -> 1 changes