Fix Python 3 pylint errors
    
    ************* Module ipaserver.install.ipa_kra_install
    ipaserver/install/ipa_kra_install.py:25: [W0402(deprecated-module), ] Uses of a deprecated module 'optparse')
    ************* Module ipapython.install.core
    ipapython/install/core.py:163: [E1101(no-member), _knob] Module 'types' has no 'TypeType' member)
    ************* Module ipatests.test_ipapython.test_dn
    ipatests/test_ipapython/test_dn.py:1205: [W1505(deprecated-method), TestDN.test_x500_text] Using deprecated method assertEquals())
    ************* Module ipa-ca-install
    install/tools/ipa-ca-install:228: [E1101(no-member), install_master] Instance of 'ValueError' has no 'message' member)
    install/tools/ipa-ca-install:232: [E1101(no-member), install_master] Instance of 'ValueError' has no 'message' member)
    
    Signed-off-by: Christian Heimes <cheimes@redhat.com>
    Reviewed-By: Simo Sorce <ssorce@redhat.com>
    Reviewed-By: Stanislav Laznicka <slaznick@redhat.com>