Added Mousetrap reset whenever keybindings get reloaded.

It is required to reset the Mousetrap.js library as turbolinks does not refresh the page. Therefore some old keybindings might still be present.

To reproduce create the following steps:

1) Create a page which lists all entities of type X (index.html.erb)
2) Create a detail page for an entity of type X (show.html.erb) incl. an edit link (with keybinding 'e').
3) Enable turbolinks
4) Visit the index page, then navigate to one of the entities.
5) Go back to the index page and press 'e'. You get now to the edit view of the previous visited entity.