--cert-selector with string argument incorrectly fails when a Value includes a space

[chalford]

Apologies if I have missed some documentation that describes how to do this.

getStringMap() in credentials.go does strings.Split(s, " ") on the --cert-selector argument. If the Value is a DN that includes components with spaces, these get split incorrectly.

Perhaps either of these would be a way to approach the problem:

1. The --cert-selector argument provides some way to substitute spaces with another character, or,
2. The --cert-selector argument uses a different separator character (than space) for each key-value pair

A workaround exists by using the file:// argument with a JSON file, where a space in the Value field works as expected.

[13ajay]

You're right, the current workaround is to use a file as the selector as you said. I had started to address this issue in #66, but that requires some updates at this point. I'll discuss further with my colleagues and hopefully address it soon.