Translate pure JS labels

I finally used the CMFPlone technique to define a list of js var that will be useable after in the js methods.

The js file is directly called in documentviewer.pt so not defined in portal_javascript.  It is called thru a view call so it will be cached by the browser.

I added also some missing translations...

This should close #24 

Please have a look and merge ;-)

Gauthier