Make es6-promise a peer dependency so that users don't end up with two copies of the promise library and instanceof works correctly.
Make es6-promise a peer dependency so that users don't end up with two copies of the promise library and instanceof works correctly.

kentonv/node-capnp,dwrensha/node-capnp,jzjzjzj/node-capnp,dwrensha/node-capnp,jzjzjzj/node-capnp,jzjzjzj/node-capnp,martindale/node-capnp,dwrensha/node-capnp,jzjzjzj/node-capnp,kentonv/node-capnp,dwrensha/node-capnp,martindale/node-capnp,kentonv/node-capnp,martindale/node-capnp,martindale/node-capnp