Downloading Data From Websites Broken

[jjacobson95]

Many websites have made changes to how they allow their data to be downloaded. Code needs to be reworked for the following datasets.

Datasets affected:

• HCMI (GDC)
• Depmap / broad sanger. (depmap)
• Pancreatic (Silverchair)
• Pubchem (rate limits)

[sgosline]

Is this a duplicate of #471? how long will it take to update each one? Our priority is getting the paper out, so this wil have to wait until after that.