Add support for SSH public keys to user and host objects.
    
    This patch adds a new multivalue param "sshpubkey" for specifying SSH public
    keys to both user and host objects. The accepted value is base64-encoded
    public key blob as specified in RFC4253, section 6.6.
    
    Additionaly, host commands automatically update DNS SSHFP records when
    requested by user.
    
    https://fedorahosted.org/freeipa/ticket/754