Rewritten generic_mailer view to HAML + added gettext calls
Adjusted specs for generic_mailer to accept HAML rendered HTML

When rendering the HTML mail using HAML, some extra whitespace characters (newlines, spaces) are added around the tags.
Merge pull request #1018 from skateman/gettext-haml-generic_mailer

Rewritten generic_mailer view to HAML + added gettext calls