Finish work replacing the errors module with errors2

Once this is committed we can start the process of renaming errors2 as errors.
I thought that combinig this into one commit would be more difficult to
review.

install/tools/ipa-compat-manage

@@ -26,7 +26,7 @@ try:
     from ipapython import entity, ipautil, config
     from ipaserver.install import installutils
     from ipaserver.install.ldapupdate import LDAPUpdate, BadSyntax, UPDATES_DIR
-    from ipalib import errors, errors2
+    from ipalib import errors2
     import ldap
     import logging
     import re