Address xfail tests in rolling.apply

[mroeschke]

A few tests had to be xfailed in #29 (e.g. https://github.com/twosigma/pandas/pull/29/files#diff-ec0ad82c276c1d0caa9df6105adb8cd7R135). The failures fit in some categories since we are using nopython mode:

1. Only builtin or numpy objects are supported (e.g. no pandas objects)
2. No complex flows (e.g. error handling)
3. *args, **kwargs are not supported

Address these as they are supported in future releases in numba