Forces uppercase uuid and mac_id in calls to the boot and node endpoints

When testing the latest changes to Hanlon with the changes submitted by @jcpowermac to support RHEL 7, an edge case developed where the node was checking in and registering using a SMBIOS UUID with lower-case letters in it's hexadecimal UUID values, while the node's hardware identifier in Hanlon had the same UUID but with uppercase letters. The result was that the node was bound to an `active_model`, but when it rebooted it booted back into the Microkernel (since the hexadecimal values in the uuid passed into the boot endpoint by the chain boot process had lower-case letters in them).

The changes in this PR modify the node checkin and registration process (along with calls to the boot endpoint) so that the hexadecimal numbers included in any of the `uuid`, `mac_id`, or `hw_id` values received by Hanlon through these RESTful endpoints are converted to uppercase. This ensures a match between the identifiers passed in through these endpoints and the hardware identifier for the node, even when lowercase letters are included in the calls to these endpoints.