Retrieves an access token for Cisco Secure Email Threat Defense. This token can then be used with other atomics for Email Threat Defense.

Target: HTTP Endpoint for "api.<region>.etd.cisco.com" with a path of "/v1"

Account Key: HTTP Basic Authentication with your client ID as the username and secret as the password

Steps:
[] Build the authorization header
[] Attempt to fetch an access token
[] Check if the request was successful:
[]> If it was, attempt to extract the token and set the output variables
[]> If it wasn't, output an error

More information about this API: https://developer.cisco.com/docs/message-search-api/#!authentication-api

Cisco Secure Email Threat Defense - Get Access Token