Implement default align

@yuki-kimoto How about this ?

```perl
#!/usr/bin/env perl
use strict;
use warnings;

use utf8;
use Text::UnicodeTable::Simple;

binmode STDOUT, ":utf8";

my $t = Text::UnicodeTable::Simple->new(alignment => Text::UnicodeTable::Simple::ALIGN_RIGHT);

# using alias method of Text::ASCIITable
$t->setCols('Id','Name','Price');
$t->addRow(1,'りんご',24.4);
$t->addRow(2,'パイナップル',21.2);
$t->addRowLine();
$t->addRow(3,'パッションフルーツ',12.3);
$t->addRowLine();
$t->addRow('','Total',57.9);
print $t->draw;
print "\n";
```

![default-alignment](https://cloud.githubusercontent.com/assets/554281/4055142/1a3cf260-2d9d-11e4-9c41-07a3457b4187.png)