Move javascript code from device's show view

Javascript code to show graph is moved to graphupdater.js file on
assets.
Merge show file
Update graph with datepicker
Add authentication filter on device controller
Root to devices index in case user logged in
Merge branch 'feature/web_devices' of github.com:alealmuna/sensa into feature/web_devices
Add removed libraries on show

Add d3 an rickshaw javascripts.
Show created_at field instead of measured_at

When rendering the graph show the created_at value on the x axis.
Fix Y axis on chart

Device's chart shows the measured value axis after the orientation label
on the axis definition was deleted and the axis was rendered.
Add date on chart hover label