Fix crash when no issues in github project

Fixes #22 urllib2.HTTPError: HTTP Error 410: Gone when no issues in
github project as well.

Error detected while processing function <SNR>14_setupOmni:
line    8:
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "<string>", line 59, in pullGithubAPIData
  File "/usr/lib64/python2.7/urllib2.py", line 127, in urlopen
    return _opener.open(url, data, timeout)
  File "/usr/lib64/python2.7/urllib2.py", line 410, in open
    response = meth(req, response)
  File "/usr/lib64/python2.7/urllib2.py", line 523, in http_response
    'http', request, response, code, msg, hdrs)
  File "/usr/lib64/python2.7/urllib2.py", line 448, in error
    return self._call_chain(*args)
  File "/usr/lib64/python2.7/urllib2.py", line 382, in _call_chain
    result = func(*args)
  File "/usr/lib64/python2.7/urllib2.py", line 531, in http_error_default
    raise HTTPError(req.get_full_url(), code, msg, hdrs, fp)
urllib2.HTTPError: HTTP Error 410: Gone

Signed-off-by: Igor Gnatenko <i.gnatenko.brain@gmail.com>