Issue #27: Localization
- first steps with localization:
	- added some locale files, took them from bliss as base
	- set in confid/application.rb defalt language to DE
Issue #27: localization
- page headings and titels are set with variable (more consistency)
- localization is done
  - all ui elements are either hardcoded named in german or via german localization file
- customer sex attribute values are now "m" and "f"
Merge branch 'localization_#27' of https://github.com/fadendaten/skiRenting into localization_#27

Conflicts:
	app/assets/stylesheets/form.css.scss
	app/views/addresses/_list_by_type.html.haml
	config/locales/de.yml
	config/locales/simple_form.de.yml