Fix forward slash character handling in credential IDs

[chriskilding]

trafficstars

Fix forward slash character handling in credential IDs, so that they can be displayed in the Web UI without breaking

Fixes #205

[chriskilding]

The basic idea will be to wrap the credentials with the CredentialsWrapper proxy class.

This includes the magic ingredient

public String getUrlName() {
            return Util.rawEncode(id);
}

Which urlencodes the credential ID, making any forward slash characters within it safe.

But we need to figure out how the CredentialsWrapper is passed around and used.

[chriskilding]

Closing as this is a problem across all credential providers (including the default one) - not just this one - so it's not something that can be fixed here.