Replace nose with unittest and pytest

* Replace raise nose.SkipTest with raise unittest.SkipTest
* Replace nose.tools.assert_equal(a, b) with assert a == b
* Replace nose.tools.raises with pytest.raises
* Convert @raises decorator to pytest.raises() but just for relevant
  lines.
* Remove nose dependency

I left the nose_compat pytest plugin in place. It can be removed in
another request in case it is no longer used.

https://pagure.io/freeipa/issue/7301

Signed-off-by: Christian Heimes <cheimes@redhat.com>
Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>

ipatests/test_cmdline/cmdline.py

@@ -21,9 +21,9 @@
 Base class for all cmdline tests
 """
 
-import nose
 import distutils.spawn
 import os
+import unittest
 
 from ipalib import api
 from ipalib import errors
@@ -65,6 +65,6 @@ class cmdline_test(XMLRPC_test):
             )
         super(cmdline_test, cls).setup_class()
         if not server_available:
-            raise nose.SkipTest(
+            raise unittest.SkipTest(
                 'Server not available: %r' % api.env.xmlrpc_uri
             )