Express into RNA-seq pipeline

@roryk if you could take a look. 
./run_test.sh rnaseq is working for me, so i didn't break anything :)
I tested star dataset adding `rsem: true` to the yaml file, and it worked. As well, tested with real data, two human samples. 
We need to re-do tophat transcriptome indexes to get it working, other-wise the pipeline will raise an error. 
Feel free to comment any part, I tried to add it as I thought it fits better with the other code. Or change anything you see could be better.