GeoIPException is not imported, so use generic Exception class

When using GeoIP without defining the GeoIP library path, an exception is thrown. However, an incorrect exception class is used an the real exception is hidden.

Expected result:

    Exception at /test/geoip/
    Could not find the GeoIP library (tried "GeoIP"). Try setting GEOIP_LIBRARY_PATH in your settings.
    Request Method:	GET
    Request URL:	http://localhost:8000/test/geoip/
    Django Version:	1.4
    Exception Type:	Exception
    Exception Value:	
    Could not find the GeoIP library (tried "GeoIP"). Try setting GEOIP_LIBRARY_PATH in your settings.

Actual result:

    NameError at /test/geoip/
    name 'GeoIPException' is not defined
    Request Method:	GET
    Request URL:	http://localhost:8000/test/geoip/
    Django Version:	1.4
    Exception Type:	NameError
    Exception Value:	
    name 'GeoIPException' is not defined
    Exception Location:	/django/contrib/gis/geoip/libgeoip.py in <module>, line 22