Update strings to new naming decision.

* The add-on is now called
  "Dontprint -- paperless printer for scientists"

* In the UI, prefer the brand-agnostic term "e-reader" over
  "Amazon Kindle" wherever things apply to general e-readers.
Add first list of builtin journals.

  * Update DATABASE_VERSION to 20140216.

  * Implement function updateDatabase(). If executed, it loads a subscript
    that contains some sample data for builtin journals. The rationale
    for the additional indirection is that UpdateDatabase() is only called
    after updates of Dontprint and therefore we don't want to load the list
    of builtin journals every time Firefox starts (the list of builtin
    journals will hopefully become rather long in future versions).

  * At the moment, the list of builtin journals is very short and mainly
    serves as a playground to test the way journal filters and, especially,
    priorities are handled.
Add context menu to Dontprint-button on Zotero pane