Changes:
* app.core: add ngSanitize (although I don't think I'm currently using it)
* Auth: replace toastr with logger to logAndNotify on login/logout
* README:
    * generate table of contents for Readme and inline link
      top-level headings
    * start to document and explain philosophy behind app core
* Grunt:
    * change final watch task from default to reload to prevent running
      open on every save
    * add but comment out express-keepalive since, not sure if needed