Remove duplicate and unused utility code

IPA has some unused code from abandoned features (Radius, ipa 1.x user
input, commant-line tab completion), as well as some duplicate utilities.
This patch cleans up the utility modules.

Duplicate code consolidated into ipapython.ipautil:
    {ipalib.util,ipaserver.ipautil,ipapython.ipautil}.realm_to_suffix
    {ipaserver,ipapython}.ipautil.CIDict
            (with style improvements from the ipaserver version)
    {ipapython.entity,ipaserver.ipautil}.utf8_encode_value
    {ipapython.entity,ipaserver.ipautil}.utf8_encode_values

ipalib.util.get_fqdn was removed in favor of the same function in
ipaserver.install.installutils

Removed unused code:
    ipalib.util:
        load_plugins_in_dir
        import_plugins_subpackage
        make_repr (was imported but unused; also removed from tests)

    ipapython.ipautil:
        format_list
        parse_key_value_pairs
        read_pairs_file
        read_items_file
        user_input_plain
        AttributeValueCompleter
        ItemCompleter

    ipaserver.ipautil:
        get_gsserror (a different version exists in ipapython.ipautil)

ipaserver.ipautil ended up empty and is removed entirely.

https://fedorahosted.org/freeipa/ticket/2650

ipaserver/install/ldapupdate.py

@@ -79,7 +79,7 @@ class LDAPUpdate:
             krbctx = krbV.default_context()
             try:
                 self.realm = krbctx.default_realm
-                suffix = util.realm_to_suffix(self.realm)
+                suffix = ipautil.realm_to_suffix(self.realm)
             except krbV.Krb5Error:
                 self.realm = None
                 suffix = None