Watcher cannot specify starting revision.

[mikedoug]

This is keenly important to avoid having to use locking. This is trivial to fix in WatchBuilder class by adding something like this to it:

public fromRevision(revision: string, increment: number) {
    this.request.start_revision = new BigNumber(revision).add(increment).toString();
    return this;
}

The revision I am passing in here is from a previous call to get all of the keys under a prefix. I want to be able to tell it to use that revision plus one (hence the increment). I'm not sure if that is a string or whatnot. I would have done a pull request myself, but I've not dabbled in Typescript, and when I tried to run the tests unmodified they blew up on me.

[connor4312]

This has been added and published in 0.2.12. Thanks for your suggestion!