Fix ->shorten() returning hash rather than string in commandline app

[bpj]

In the commandline app the line

print $bitly->shorten(URL => shift @ARGV), $/ while @ARGV;

should be changed into

print $bitly->shorten(URL => shift @ARGV)->{url}, $/ while @ARGV;

or even better

for ( @ARGV ) {
    my $url = $bitly->shorten( URL => $_ );
    $url = $url->{url} if 'HASH' eq ref $url;
    print $url, $/;
}