Check SHA1 sum of the downloaded s3cli
Check SHA1 sum of the downloaded s3cli

[#105488550](https://www.pivotaltracker.com/story/show/105488550)

Signed-off-by: Edwin Xie <6bc24e9c160281972837d9e13287696d26612564@pivotal.io>

barthy1/bosh,barthy1/bosh,barthy1/bosh,barthy1/bosh