don't assume first UPS event has a location

e.g. package 1Z05R2W10378274146 has a first event:
"The shipper has requested a Delivery Intercept for this package. /
Return to sender pending."
This event has no location associated with it.
Fixing a few tiny mistakes
Merge pull request #133 from Shopify/refactoring/pr_128_dont_assume_ups_event_has_a_location

don't assume first UPS event has a location