JUnit reporter testsuite counts are not consistent with number of testcases

The test code:

``` c++
TEST_CASE("Single TEST_CASE", "single")
{
CHECK(true);
CHECK(true);
CHECK(false);
}
```

produces the following JUnit reporter output:

``` xml

at /file_path_redacted/bug.cpp:14

```

I'd expect the number of `testcase` elements to match the value of the `tests` attribute on the `testsuite` element. It appears that the attribute is instead counting the number of individual assertions that are made. I believe that is misleading behavior (and unfortunately, I'm not sure the semantics of the JUnit format are terribly clear).