Generate uuids and timeuuids on JS side.

    Our new C* client doesn't convert Dates to timeuuids, which are safe for
    use as a unique ID in a distributed system. Instead, it converts Dates
    to timestamps. We don't want that.

    In order to create timeuuids, we need to generate v4 uuids. While our
    C* client library uses the node-uuid library, it doesn't expose any methods
    to generate uuids (v1 uuid) or timeuuids (v4 uuid). So, we had to include
    that as a dependency.

    I haven't investigated quirks in the node-uuid or Java uuid generator, so
    to hedge bets, rather than generate some timeuuids by passing `NOW()` into
    the cql, and some timeuuids by calculating `uuid.v4()` on the JS side,
    we'll just *always* use node-uuid for now. If there are quirks, at least
    they will be consistent and caused by one, not two, libraries.

    Fingers crossed.