add mail gem and update ruby-plsql to v0.5.2
class for deleting user
subclasses for employee and guests
ignore rbenv-version file and .env file
add a template directory for mail templates
delete old gitmodules file
mail wrapper for account mails
mail wrapper for summary mails
summary mail template for guest accounts
ignore templates/abschiedsbriefe
wrapper class for account
wrapper class for global date computations
beta version of guest class
hook up guest class and compute application_root path