Returns an XML payload used to indicate if the sign in credentials provided are valid.  When valid credentials are provided the XML payload will return the vendor company and email. 

Sample Request URL:
[End Point URL]/?do=cnt.getservice&service=authenticateVendor

Parameter Options:
*apiKey: Valid API key
*username: Text string of the person’s username
*password: Text string of the person’s password

Sample Valid XML Payload:  See REST_authenticateVendor.xml

Sample Invalid XML Payload:
<authentication result='invalid'><firstname /><lastname /><company
/><email /></authentication>