Quote command so paths with whitespace work

[AlicanC]

Summary

If the project is in a path with whitespace (/Users/bleh/My Stuff/project/), running binaries (yarn run eslint) doesn't work. I quoted cmd to solve this issue.

A better way to solve this could be passing cmd and args separately down to child.jss spawn() and quoting or escaping there, but that would require too much API change.

Comments?

Test plan

Reproduce:

mkdir "some dir"
cd "some dir"
git clone [email protected]:yarnpkg/yarn.git
cd yarn
yarn
yarn run eslint

[nodesocket]

Seems this commit broke yarn run command arg1 arg2.

See: issue 733