Add getModel() for getting machine model name

- Not SMC related, but for https://github.com/beltex/swift-smc/issues/4
Initial implementation of machineProfile()

- Issue https://github.com/beltex/swift-smc/issues/4
- Writes to JSON
- Helper methods to get all valid TMP keys and fan info
- Static array for TMP enum to be able to enumerate all values. Not ideal
  solution, but seems to be the current best.
Cleanup to machineProfile related methods

- Make getFanInfo() private, as returning a map with custom keys not helpful
  to user
Merge branch 'sys-info'

- Closes issue https://github.com/beltex/swift-smc/issues/4