This function first compares all crime pairs using compareCrimes,
then uses estimateBF to estimate the log Bayes factor for every pair.
Next, it passes this information into hclust to carry out the
agglomerative hierarchical clustering. Because hclust requires
a dissimilarity, this uses the negative log Bayes factor.
References
Porter, M. D. (2014). A Statistical Approach to Crime Linkage.
arXiv preprint arXiv:1410.2285..
http://arxiv.org/abs/1410.2285