[infer][PR] Update supported opam version to 1.2.2
[infer][PR] Update supported opam version to 1.2.2

Summary:
Fixes #588
Closes https://github.com/facebook/infer/pull/589

Reviewed By: mbouaziz

Differential Revision: D4666015

Pulled By: jvillard

fbshipit-source-id: 7372655

ropas/infer,blzq/infer,blzq/infer,jsachs/infer,ryoon/infer,ropas/infer,jvillard/infer,facebook/infer,facebook/infer,jsachs/infer,jvillard/infer,ropas/infer,ropas/infer,jvillard/infer,ryoon/infer,facebook/infer,jsachs/infer,ryoon/infer,ryoon/infer,facebook/infer,facebook/infer,facebook/infer,blzq/infer,jsachs/infer,blzq/infer,jsachs/infer,jsachs/infer,blzq/infer,ropas/infer,facebook/infer,blzq/infer,jvillard/infer,ryoon/infer,jvillard/infer,ropas/infer,jvillard/infer,jvillard/infer,ryoon/infer