sudo commands under debian sub section. git cache conditionals optional. removed gnome specific command. 

Change browserid.org urls to persona.org, introduce static.login.persona.org for all static resources.

issue #1367

by default, run all tests during npm test, and emit clear errors when dependencies (mysql or phantomjs) aren't installed

update package.json with new dependencies.  update getting started instructions with how to use npm to install deps.  ref package.json from the README rather than duplicating information.  closes #60 (equivalent).

initial stubbing of db.js tests, also generalize db.js so that the path where the database resides may be configured