Lock exponent/js .flowconfig to v0.42.0, until we have time to upgrade flow
Lock exponent/js .flowconfig to v0.42.0, until we have time to upgrade flow

fbshipit-source-id: cb02e85

exponent/exponent,exponent/exponent,exponent/exponent,exponent/exponent,exponentjs/exponent,exponentjs/exponent,exponent/exponent,exponentjs/exponent,exponentjs/exponent,exponent/exponent,exponentjs/exponent,exponentjs/exponent,exponentjs/exponent,exponent/exponent,exponent/exponent,exponentjs/exponent,exponentjs/exponent,exponent/exponent