Applied tier0 and tier1 marks on unit tests and xmlrpc tests

Web UI tests were marked as tier1 tests.

The tier system is intended to be used together with CI system
to make sure the more complicated tests are being run only
when all of the basic functionality is working.

The system is using pytest's marker system. E.g. an invocation of
all tier1 tests with listing will look like:

    $ py.test -v -m tier1 ipatests

or in case of out of tree tests:

    $ ipa-run-tests -m tier1

Reviewed-By: Ales 'alich' Marecek <amarecek@redhat.com>

ipatests/test_cmdline/test_ipagetkeytab.py

@@ -32,6 +32,7 @@ import tempfile
 import gssapi
 from ipaserver.plugins.ldap2 import ldap2
 from ipapython.dn import DN
+import pytest
 
 def use_keytab(principal, keytab):
     try:
@@ -52,6 +53,8 @@ def use_keytab(principal, keytab):
         if tmpdir:
             shutil.rmtree(tmpdir)
 
+
+@pytest.mark.tier0
 class test_ipagetkeytab(cmdline_test):
     """
     Test `ipa-getkeytab`.