Update Marionnette version to avoid Backbone conflicts

[gregorylegarec]

I was experiencing this error in my environment when trying to run cozy-proxy.

backbone.marionette.js:3232 Uncaught TypeError: Cannot read property 'radio' of undefined

@CPatchane was not able to reproduce on his own environment.

First fix was to follow this Stack Overflow answer : http://stackoverflow.com/questions/35802424/backbone-marionette-and-webpack-uncaught-typeerror-cannot-read-property-radi and update webpack.config.js

resolve: {
    alias: {
        backbone: path.join(__dirname, 'node_modules', 'backbone', 'backbone')
    }
}

As this fix gave us evidence of a Backbone version problem, we investigated this option. We finally discovered that updating Marionette version in client/package.json was also fixing my environment, and was still working on @CPatchane's one.

[gregorylegarec]

Thanks to have a quick review on this, @aenario (If you don't have time, feel free to assign anyone else)

[CPatchane]

After investigating with @gregorylegarec, this issue seems to be related to the marionette version which was not fully compatible with Backbone v1.3.3 (see changelog), so use the v2.4.6 of Marionette should correctly fix that issue.