Implement EXFrame::didSetProps; clean up reload logic; fix validating manifest
Implement EXFrame::didSetProps; clean up reload logic; fix validating manifest

fbshipit-source-id: fcceb23

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