WIP incorporate prototype PCA
Rough, but working PCA

- With selectable dimensions!
Fix dimension selection
Fix PCA calculation
Convert to RMS distances
Include computing the distance matrix (not used)
Add option to display counts at counts-per-million (CPM)
Make the parallel-coordinates plot as wide as possible
Add a couple of FAQ entries to the README
Update docs for 'local installation' to suggest using degust.py
Tweak help text for "min read count"
Merge branch 'master' into pca

Conflicts:
	app/js/compare.coffee
Improve selectors to allow multiple heat maps on a  page
Add a wrapper for web workers.
Split out the heat map clustering into a web-worker

- Should make page more responsive for large number of genes
- Also better clustering by first choosing "most extreme" gene
Update colours in heat map, table and kegg image.

Red is "up", blue is "down"
Add a legend to the heatmap
Make heatmap always fc relative to row average
Improve show heatmap "thinking" while computing clustering
Merge branch 'master' into pca