@allow-large-files [vissl][PR] V0.1.6 build fairscale pip pckg @allow…

…-large-files (facebookresearch#465)

Summary:
1. Add fairscale to pip binary, as pypi won't allow you to have direct dependencies.
2. Change tutorials / installation from source instructions to reflect above.
3. I also moved up conda installation instructions to be first, since I think we should promote using conda (easier to manage environments).

Pull Request resolved: facebookresearch#465

Reviewed By: QuentinDuval

Differential Revision: D32069671

Pulled By: iseessel

fbshipit-source-id: 54180d5882afa351c4c725bf4dbfa228b38cd7d5

Apply bottlers changes from PR208

Apply bottlers changes from PR208