Description of problem:
When a user requests membership to a language, the email sent to admin contains the string "jsf.email.joinrequest.RoleRequested", perhaps an untranslated string?

Version-Release number of selected component (if applicable):
3.x

How reproducible:
Easy always

Steps to Reproduce:
1. Sign in as translator
2. Select a language the translator is not a member of
3. Click Request to Join Team
4. Fill in the form and click send

Actual results:
The email received contains the string "jsf.email.joinrequest.RoleRequested"

Expected results:
Should be something like Roles Requested

Additional info:
Dear Language Team Coordinator,

Zanata user 'translator' with id 'translator' is requesting to join the en-US (English (United States)) Language Team
jsf.email.joinrequest.RoleRequested

    Translator
    Reviewer

translator has included the following message with their request:...