show isbn on book edit form
make adding a new book work again
Amsterdam50 app config
style change
move site-specific css styles
move menublock to submenu
rework front and about page
fixes for light amsterdam50 theme
run on Heroku
allow to use environment for secrets
allow to config smtp settings
add recent items to frontpage
restyle loans page
show books in blocks (except search)
add tag editor with autocomplete
allow to serve cover images by Google

Conflicts:
	app/helpers/application_helper.rb
	config/application.yml
don't store cover images for Heroku
more flexible sidelinks structure
fit in sidelinks in amsterdam50 theme
improve user profile