Bug fix to bad coordinate reading on private IPs.

[UmanShahzad]

Closes #10

Fixes an issue where geolocation data isn't available (e.g. for private IPs) and we try to retrieve it by giving an index, without checking if it's valid for the list.

Was able to reproduce the issue in #10 with:

>>> details = handler.getDetails('10.62.100.139')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/mslm/dev/ipinfo/python/ipinfo/handler.py", line 53, in getDetails
    lat, lon = coords[0], coords[1]
IndexError: tuple index out of range

After the fix:

>>> details = handler.getDetails('10.62.100.139')
>>> details.all
{'ip': '10.62.100.139', 'bogon': True, 'country_name': None, 'ip_address': IPv4Address('10.62.100.139'), 'latitude': None, 'longitude': None}
>>> details.latitude
>>> details.longitude
>>> details.bogon
True

and for public IPs:

>>> details = handler.getDetails('9.9.9.9')
>>> details.all
{'ip': '9.9.9.9', 'hostname': 'dns.quad9.net', 'city': '', 'region': '', 'country': 'FR', 'loc': '48.8582,2.3387', 'org': 'AS19281 Quad9', 'country_name': 'France', 'ip_address': IPv4Address('9.9.9.9'), 'latitude': '48.8582', 'longitude': '2.3387'}
>>> details.latitude
'48.8582'
>>> details.longitude
'2.3387'
>>> details.loc
'48.8582,2.3387'
>>> details.country
'FR'

[UmanShahzad]

@coderholic and/or @jhtimmins can you review/merge/update pypi?