replaced freemarker email templates with mustache, using JMustache
implemented depositor email notifications with a unit test
added failure message sending (not triggered by failed message sending)
link to deposit page still present, even when deposit record is not ingested (redis state will be rendered)
changed up the mocks for email unit.
Merge pull request #121 from gregjan/ingest-mail

replaced freemarker email templates with mustache, using JMustache