corrected use of URL within blocktrans

fixed wrong syntax using blocktrans

added trans and blocktrans

Created a mockup login and logout function and added login required as decorator for, among others, the settings page. ...

Authorized user names and passwords can be found in views.py in the function login_required (see the dictionary "valid_users"). This needs to be changed later when the authenticate functionality in the rest server is implemented.

Added a block "links" to base.html and added some links on top of the page to a few of the templates. Also added missing mock data for three fields.

Added a mass subscription function and changed the redirekt after creating a list to let the list creators decide what they want to do next.

Added a function to update the changes made to the list settings and added missing <form>-parts in settings.html.

Created one massive form for the settings page.

Corrected the decorators and started with the settings view and forms.