Fix distorted images in genome dashboard

Many of the images in the new genome dashboard application look distorted.

For example, the image for the cow genome looks great when viewed on its own, but in the Dashboard App it looks compressed in the horizontal dimenion.

Compare:

• https://test.bioviz.org/genome-dashboard

to

• https://test.bioviz.org/public/images/B_taurus.jpg

The problem is that the images need to be perfectly square to look nice in the Dashboard.

For this task, examine each image and crop it as needed to make it look nice.

Before starting work on this, consult with Sameer Shanbhag (app developer) for advice or tips he may have.

Also, please note that all pull requests should go to master branch on his repository.

Use this repository for branching and submitting PRs: https://bitbucket.org/lorainelab/genome-dashboard

(Once Sameer is back we'll submit PRs to his upstream repo.)