Problems changing entity ID

[veselov]

I found a few nasty problems trying to set a custom entity ID.

1. If entity ID is changed, and new credentials are not provisioned, /metadata call fails (I believe SAML operations will also fail). This is because there is no keystore for the new entity ID
2. If entity ID is changed, and new credentials are provisioned, /metadata call still fails. This is because key manager does not have credentials for the entity ID
3. (not as related), changing idp.passPhrase leads to failures because key password is hardcoded in shared configuration

I'm gonna post a PR in a bit.