bulkGeocode: Add check for undefined location property

[gcstarr]

When using bulkGeocode in arcgis-rest-geocoder If geocoding returns 0 candidates for a given address, the value returned for that address is:

{
  "address": "",
  "score": 0,
  "attributes": { . . . }
}

Due to the code assuming the location property is present, this results in:
TypeError: Cannot set property 'spatialReference' of undefined
in the following line of code:
address.location.spatialReference = sr;

A quick way to reproduce this is to try a bulkGeocode that includes a nonsense singleLine like sldafjsedoifhsoaifhsdoifh.

[coveralls]

Coverage remained the same at 100.0% when pulling cba60dc on gcstarr:AddCheckForBulkNullResult into b84bad2 on Esri:master.

[coveralls]

Coverage remained the same at 100.0% when pulling cba60dc on gcstarr:AddCheckForBulkNullResult into b84bad2 on Esri:master.

[jgravois]

great catch. thx!