initial commit
add metaseq-demo.py
add de-example.py
make download_data.bash cross-platform

assume curl on mac; wget on linux.  also exclude items in filelist
starting with "#"
add gffutils-clean-gencode.py
add hg19.genome
add de-example.ipynb
rm de-example.py; de-example.ipynb is authoritative version
rm older metaseq-demo.py
add prepare-output.sh
Merge branch 'master' of https://github.com/daler/metaseq-biotrac56