integration of guest account in login form

todo: improve CSS and compile help and information links and content
first step to implement multi libray account
configure the possible library locations
merge last development into feature/shibboleth2

Merge branch 'development' into feature/shibboleth2
Merge branch 'development' into feature/shibboleth2
Merge branch 'development' into feature/shibboleth2
no popup dialogs for Shibboleth login

using a Shibboleth login means to leave the application window and to use the login page of an external IDP
this makes it very complex (if not impossible) to capture the whole workflow within a dialog popup box
(as it is done for more easier Library system authentication where VuFind is always in control of the workflow)

Therefor I need a possibility to send the user to the default login page even this not so good related to usability aspects

This commit implements the mechanism to control the different workflows depending on the different Authentication methods