add GetRegionName

The region code returned from City queries is not useful by itself.  To
turn this into a human readable region, we can either query the
region.csv file by hand or call the GeoIP_region_name_by_code which
contains a generated lookup table to do the mapping for us.
Add test for GetRegionName
Merge pull request #7 from dgryski/get-region-name

Add GetRegionName
Download helper doesn't need perl 5.14
Fix SetCustomDirectory
Protect calls to GeoIP_region_by_addr with our mutex

Tracing through the call stack we have:
GeoIP_region_by_addr
which calls _get_region
which calls GeoIP_assign_region_by_inetaddr
which calls_GeoIP_seek_record
which clobbers our global netmask.
Expand comment for the mutex
GeoIP_record_by_addr also mutates netmask
Merge pull request #9 from dgryski/mutex-for-region-by-addr

Protect calls to GeoIP calls with our mutex