Pin the browserstack-local binary to the release

[punkeel]

Expected Behavior

browserstack-local-nodejs should pin a specific release of the browserstack-local binary, which is manually bumped by users.
Additionally, it would be great if we could store offline copies of the binary (yarn offline style?) rather than download it from S3 on every CI run.

Actual Behavior

#114 broke our CI. We can't rollback the binary as it's outside of our control, and we can't easily pinpoint the issue as we didn't bump anything.

[abhishekchoudhary]

Valid, we've pulled this into our short term roadmap. ETA: 12 weeks.