Use clearInterval instead of non-existing cancelInterval

Programming is hard :(
Use linkTo helper in navigation template

Index now doesn't redirect to devices, so a landing page is shown.
Don't show App.StatsView for the whole application
Update Ember.js to latest version
Add Ember-Data
Massive changes

This commit contains many changes, which should have been split into
smaller ones but once in the Matrix, the flow was too big to interupt.
Next commits will be smaller, I hope ...

The following changes have been made:

- Possibility to list studies and create a new one
- Show a study and add new events
- Compile all the JS into a single app.js
- ...
Merge branch 'dev'