MAP: Fix following for MAP Email GETMessage:

- Remove extra ContentType string encoded in email
  BMsg composed for GetMessage response.

- Hardcode email Attachment feature flag as always false,
  as GET email attachments feature is not yet implemented.

- Remove extra CRLF included within headers before
  emailBody message.

Change-Id: I52795152c745536978105decdc08018ea80f2dfa