SDO enable separate cert in call to exchange api

[bmpotter]

• [x] Currently the Horizon SDO support uses in exchange api calls the same cert it passes to the edge nodes. Enable a separate cert used for the exchange api call, and default it to the cert that is used to listen on the sdo port.
• [x] Call the exchange version api during startup to verify the exchange url and cert we are using.
• [x] Review all of the verbose statements to ensure none of them expose private info
• [x] Generate a random node token that follows the new exchange requirements for node and agbot tokens

[bmpotter]

I verified this works in all-in-1. But there is a problem with it in IEAM, which is being addressed in issue 121.