Make JSON RPC API Command Methods Case Insensitive

[schwede]

Is your feature request related to a problem? Please describe.
When using the json-rpc api, command request were being rejected as 'unauthorized methods'. I realized that we were sending "Cmd" instead of "cmd" to send commands.

Describe the solution you'd like
Since these names are unique, I would like the api method whitelist to allow different casing. I realize that it is documented with a reference to this file (https://github.com/BallAerospace/COSMOS/blob/master/lib/cosmos/tools/cmd_tlm_server/api.rb) but allowing case variations would make the api a little more friendly to use.