Allow adding files to the send_with_template endpoints.

[johnnycupcakes]

Please allow adding files to the send_with_template endpoints. Currently, any files sent in template requests are ignored. Thanks in advance.

TemplateSignatureRequest request = new TemplateSignatureRequest();
request.setTemplateId("c26b8a16784a872da37ea946b9ddec7c1e11dff6");
request.addFile(new File("nda.pdf"));
request.setSubject("Purchase Order");
request.setMessage("Glad we could come to an agreement.");
request.setSigner("Client", "george@example.com", "George");
request.setCC("Accounting", "accounting@hellosign.com");
request.setCustomFieldValue("Cost", "$20,000");
request.setTestMode(true);

HelloSignClient client = new HelloSignClient("SIGN_IN_AND_CONFIRM_EMAIL_TO_SEE_YOUR_API_KEY_HERE");
SignatureRequest newRequest = client.sendTemplateSignatureRequest(request);