Fixed multiple issues for CloudSpokes challenge 2572

[talesforce]

Demo URL - http://67.20.109.73//dev/php_api/DocuSignSample/senddocument.php

Features Tested/ Verified

• This is the list of features I verified/ tested
• Send Document (verified all parameters and email sending)
• Send a template
• Embed DocuSign
• Get Status and Docs - Verified all operations including ViewRequestStatus, Download PDF and Start Signing

  Issues Fixed

• Current code throws a 403 error if you hit 'Choose Template' and there is no template available. I added a defensive check there.
• Removed a lot of redundant code - header code was copied in all files, moved it to a single php file and included that
• Cosmetic Change - Changed 'logout' to 'Logout'
• Changed Footer links to open in a new window