Check md5sums for downloaded data

[aidanheerdegen]

Add md5sum check to data download script:

https://github.com/BreakawayLabs/mom/blob/7511f4b964f3a28af6ecc2b3e132a95dc18fa714/data/get_exp_data.py

The md5sums are in the same directory as the data, named same as the datafile with a .md5 appended.
e,g.

-rw-rw----+ 1 nah599 ua8 524743 Jan 22 2015 torus1.output.tar.gz
-rw-r-----+ 1 aph502 ua8 55 Sep 11 09:14 torus1.output.tar.gz.md5

Should be possible to try downloading an .md5, if successful, run md5sum -c md5file

I guess not everyone will have md5sum in their path, but warn them that they should install as data integrity cannot be guaranteed?

Thanks

Aidan