mails localizations and other

list of changes:
1)
implement mail templates (closes #70) - on ui: administration->manage mail templates.
it allows to create template in other than en language.
to get this working you need to create the template for specific group of notification and set this as enabled and default;
In case when you's like to create mail that contains merged notifications in two languages  then you  need to create two templates for specific group with different lang set and: one of them must be set as default and other one as "always add"
2)
disable simple mode for SP/IDP registration form
3) minor fixes

update:
don't forget to run doctrine-cli as the new table will be created