Updated config to change empty string to null since the empty string was
hitting an isset check which caused an empty string to be used instead
of the slo url as a backup option.
Closes#2002
- Aligned and formatted config options.
- Provided way to override onelogin lib options if required.
- Added endpoints in core bookstack routes.
- Provided way to debug details provided by idp and formatted by
bookstack.
- Started on test work
- Handled case of email address already in use.
