Updated release with more instructions

New release of the ORG atlas (version 1.1.1).

1. Move atlas files to Zenodo for data storage: https://zenodo.org/record/2648292
2. Zip is used for data package.
3. Separate instructions for visualization and fiber clustering computation.
4. Fix downloading using Python script.
5. Update online instructions.
6. Add population mean T1/T2/b0 images.

First public release of the ORG-800FC-100HCP and ORG-2000FC-100HCP atlases

Add ORG-2000FC-100HCP atlas, including cluster location and tract ana…

…tomical profile