IBMCLOUD CLI: check discrepancies between apihost property and api endpoint used for login

Hi, 

I got a problem this morning that support helped me to solve.

I could not deploy a function to the eu-de host because I previously logged to eu-gb and there was a discrepancy between the apihost property (eu-de) and the endpoint used at login (eu-gb).

Since all I got was some authentication related error messages when I wanted to deploy my function.

It has taken 3 hours to solve.

Now I first set the api host property with `ibmcloud fn property set --apihost XXX` and then I login using the same endpoint : `ibmcloud login -a api.XXX`

So, in case of errors, It would be very nice to get the CLI check this.

Thanks!

François