(maint) Error message is different under Windows 2012r2

Previously, the test was expecting a failed logon to raise an error
whose message contained:

    unknown user name or bad password.

This is correct in 2008r2 and earlier, but it appears Windows 2012
changed the error message to be:

    The user name or password is incorrect.

This commit updates the test to not be sensitive to the message
text. Instead we verify that the exception contains the correct Win32
error code (ERROR_LOGON_FAILURE).
(maint) Mark taskscheduler provider tests as pending on ruby 2

The taskscheduler provider tests don't pass on Windows and ruby 2,
because the underlying win32-taskscheduler gem does not work on x64.

This commit marks the tests as conditionally pending. The tests will be
re-enabled when PUP-2881 is implemented.
(maint) Mark eventlog tests as conditionally pending on ruby 2

Previously, the tests would fail on ruby2, because under ruby 2 we are using
a newer win32-eventlog gem, whose constants are in a different namespace than
the version of the gem we are using for ruby 1.9.

This commit marks the tests as conditionally pending when running under Windows
and ruby2. The tests will be re-enabled when PUP-2889 is implemented.