disable/ignore multi-arch client tests on lucid

I'll leave it to you on how to fix them, but right now we have two failures. In talking with BjornT, it would be good to disable these on lucid and previous.

<<< landscape.package.tests.test_facade.AptFacadeTest.test_wb_mark_install_upgrade_non_main_arch
Stack Trace

_StringException: Text attachment: traceback
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Traceback (most recent call last):
  File "/usr/lib/python2.6/dist-packages/twisted/internet/defer.py", line 117, in maybeDeferred
    result = f(*args, **kw)
  File "/usr/lib/python2.6/dist-packages/twisted/internet/utils.py", line 191, in runWithWarningsSuppressed
    result = f(*a, **kw)
  File "/var/jenkins/workspace/landscape-client-test/label/lucid/landscape/tests/mocker.py", line 146, in test_method_wrapper
    result = test_method()
  File "/var/jenkins/workspace/landscape-client-test/label/lucid/landscape/package/tests/test_facade.py", line 1012, in test_wb_mark_install_upgrade_non_main_arch
    sorted(changes))
  File "/usr/lib/python2.6/dist-packages/twisted/trial/unittest.py", line 287, in failUnlessEqual
    % (msg, pformat(first), pformat(second)))
FailTest: not equal:
a = [('multi-arch', '2.0'), ('multi-arch:i386', '2.0'), ('single-arch', '2.0')]
b = [('multi-arch', '2.0'), ('single-arch', '2.0')]

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0.686 2
<<< landscape.package.tests.test_facade.AptFacadeTest.test_wb_mark_install_upgrade_non_main_arch_dependency_error
Stack Trace

_StringException: Text attachment: traceback
------------
Traceback (most recent call last):
  File "/usr/lib/python2.6/dist-packages/twisted/internet/defer.py", line 117, in maybeDeferred
    result = f(*args, **kw)
  File "/usr/lib/python2.6/dist-packages/twisted/internet/utils.py", line 191, in runWithWarningsSuppressed
    result = f(*a, **kw)
  File "/var/jenkins/workspace/landscape-client-test/label/lucid/landscape/tests/mocker.py", line 146, in test_method_wrapper
    result = test_method()
  File "/var/jenkins/workspace/landscape-client-test/label/lucid/landscape/package/tests/test_facade.py", line 1049, in test_wb_mark_install_upgrade_non_main_arch_dependency_error
    DependencyError, self.facade.perform_changes)
  File "/var/jenkins/workspace/landscape-client-test/label/lucid/landscape/tests/mocker.py", line 368, in failUnlessRaises
    "%s not raised (%r returned)" % (excName, result))
FailTest: DependencyError not raised ('' returned)
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