Tentative version bump and add GEOIP_SILENCE support

When calling GeoIP_new(), GeoIP_open(), or GeoIP_open_type() in the
C API via the XS stubs, add GEOIP_SILENCE to the flags. This will
stop the library from emitting noise diagnostic messages to stderr.
IP.xs: be consistent with definition of GEOIP_SILENCE

Since we explicitly define it in lib/Geo/IP.pm anyway,
we might as well use the same definition in all places. Let's
just hope it doesn't clash with another flag using that bit
position.
Merge pull request #10 from pprindeville/master

Tentative version bump and add GEOIP_SILENCE support