Standard test output is not logged to allure for failed tests, but lo…

[sphinxy]

…gged for success test.

Fixes #31

[sphinxy]

tested, now we have test output in *result.json for failing tests too.

 "name": "Test output is logged for failed test",
  "status": "failed",
  "statusDetails": {
    "known": false,
    "muted": false,
    "flaky": false,
    "message": "This failed assert is logged too along with previous output\r\nExpected: False\r\nActual:   True\nThis output of failed test should be visible in IDE and in logged allure-result/*result.json\r\n",
    "trace": "   at Xunit.Assert.False(Nullable`1 condition, String userMessage) in C:\\Dev\\xunit\\xunit\\src\\xunit.assert\\Asserts\\BooleanAsserts.cs:line 52\r\n   at Xunit.Assert.False(Boolean condition, String userMessage) in C:\\Dev\\xunit\\xunit\\src\\xunit.assert\\Asserts\\BooleanAsserts.cs:line 40\r\n   at Allure.XUnit.Examples.ExampleUnitTests.TestStandardOutputSavedToAllureForFailedTest() in C:\\_work\\Allure.XUnit\\src\\Allure.XUnit.Examples\\ExampleUnitTests.cs:line 86"
  },