Fix ipa-compat-manage and ipa-nis-manage
    
    Neither of these was working properly, I assume due to changes in the ldap
    backend. The normalizer now appends the basedn if it isn't included and
    this was causing havoc with these utilities.
    
    After fixing the basics I found a few corner cases that I also addressed:
    - you can't/shouldn't disable compat if the nis plugin is enabled
    - we always want to load the nis LDAP update so we get the netgroup config
    - LDAPupdate.update() returns True/False, not an integer
    
    I took some time and fixed up some things pylint complained about too.
    
    Ticket #83