Support multi statement update transactions

[dscape]

The current update functionality serves few purposes that are not in insert.

It was agreed it would be nicer to support something like:

  function updateUser(ghUser) {
    console.log("Trying to update github user " + ghUser.login);
    db.json.update_first(
       { github_login: ghUser.login })
         .increment('version', 1)
         .replace('github_login', ghUser.login)
         .replace('github', ghUser)
         .delete('linkedin.deletemeplease')
         .rename('meeutp','meetup')
         .push('anarray', 1)
         .addCollection('github') // also replaceCollection
         .setQuality(9)
         .replacePermissions(['a','b','c']) // also addPermissions
         .save(
           function saveCb(e) {
             if(e) {
               console.log("Couldn't update " + ghUser.login);
               return;
             }
             console.log(ghUser.login + " updated");
             return;
         });
  };

[ryangrimm]

Supporting server side updates is currently on the fence for 1.0. So I'm putting this into the 1.1 milestone for the time being.