def migrate(username, properties, message)
      headers = { 'content-type' => "multipart/related; boundary=\"#{BOUNDARY}\"" }
      make_request(:post, migration + "/#{username}/mail", body: multi_part(properties.to_s, message), headers: headers)
    end
def migrate(username, properties, message)
      headers = { 'content-type' => "multipart/related; boundary=\"#{BOUNDARY}\"" }
      make_request(:post, migration + "/#{username}/mail", body: multi_part(properties.to_s, message), headers: headers)
    end
migration performs mail migration from a local
 mail environment to GoogleApps.  migrate takes a
 username a GoogleApps::Atom::Properties dcoument
 and the message as plain text (String) as arguments.

 migrate 'user', properties, message

 migrate returns the HTTP response received from Google.