ES7 Migration - Fixing package versions

[oshalygin]

We ought to fix the dependency versions so that future fresh builds do not pull unwanted breaking change package updates. The node community is pretty inconsistent in maintaining SEMVER(which we should follow), and as such, relying on wildcards such as ^ and ~ will bite us in the long run.

[cybertk]

+1 for explicitly versioning(^), and let GreenKeeper handles the updating, GreenKeeper already provisioned.