Text Templates for mail notification

Created by: tbe

Fixed the syntax errors, travis throws two errors, one for missing content in mail, but looks like false positive. #934 (closed)

app/views/notify/issue_status_changed_email.text.erb

+Issue was <%= @issue_status %> by <%= @updated_by.name %>
+
+Issue <%= @issue.id %>: <%= url_for(project_issue_url(@issue.project, @issue)) %>
+