Changing login from oauth to basic does not clear out previous settings

[jonproch117]

• Run kfutil login successfully using oauth as the AuthType
• Cause the OAuth token server to be unable to return a token. Reason could be various, such as
  • Secret being changed on the server but not yet updated in kfutil
  • Token URL is now unreachable
• Run kfutil login again, choosing basic as the AuthType, and the hostname of a Basic auth environment
• Note that the login fails due to "failed to retrieve OAuth token", which shouldn't even be attempted for Basic auth
• Deleting $HOME/.keyfactor/command_config.json and logging in again addresses the issue

[spbsoluble]

#302 Addresses this issue