Fix function naming

Buffers whose names start with a space are “ephemeral”, as by the Emacs
Lisp manual.
Inhibit automatic checks in ephemeral buffers

The user will likely never see these buffers anyway, so there is no
point in automatically checking them
Extract autoloads detection into function
Simplify Emacs Lisp predicates

Make use of the fancy `bound-and-true-p` function and do not explicitly
check for ephemeral compilation buffers (as Flycheck now won't check
ephemeral buffers automatically anyway).
Fix Cask URL and archive name

Cask was moved into its own organisation, and consequently URLs and
package name has changed.
Improve nodejs module and provisioning

The latest nodejs Puppet module properly installs Nodejs on Ubuntu
12.04, hence we can get rid of our manual approach.
Fix test regression from 4d32595
Fix test regression from 671ea85
Remove superfluous broken tests
Fix checkdoc predicate
Do not test js3

See thomblake/js3-mode#89
Test against js3 again

This reverts commit 9e7cffc81bdf15de07eb51438585fc7ceb8318c1.
Ensure the presence of the proper nodejs repo