[task] add SendMail and TemplateRenderer service
[task] create default templates (de, en) for registration mail
[task] refactore mail service and add test class for templaterenderer
[task] change TemplateRenderer and his tests

now a custom template resolver do the job to check and retrieve the
template by name in order of custom templates in classpath and then the
default template html files
Merge pull request #145 from dacrome/OSNG-322

Osng 322