Added the script to plot plink/seq brca1 ibs matrix.

Wow - this plot is cool!  In the data, are the people that are similar all the same amount of similar?  Ignoring the diagonal, to my eye there are only two colors here.  Might be good to change the color range to better display the differences in the ibs scores or log-scale the color range.

```
> ibs_pairs <- subset(ibs_pairs, ibs_pairs$sample1 != ibs_pairs$sample2)
> mean(ibs_pairs$ibs_score)
[1] 0.04315495
> sd(ibs_pairs$ibs_score)
[1] 0.05885327
> boxplot(ibs_pairs$ibs_score)
> ggplot(ibs_pairs, aes(x=seq(1, nrow(ibs_pairs)), y=ibs_score)) + geom_point()
```