use jobReference.jobId instead, to not include the "project-id:" prefix for Job constructor

current code use the job.id from metadata in jobs.list api response to construct a Job; however
it has the full format of "project-id:jobid-........." the constructed Job from this full id
format can't be used for further acesss, like job.get job.getQueryResults
server side will return an "Invalid job ID" error; see this fixes #2736

the metadata response has jobReference.jobId is exactly needed here;

    { kind: 'bigquery#job',
      etag: '"cX5UmbB_R-S07ii743IKGH9YCYM/4xT3EKx31LcQTmnaqUafpQ2RHqU"',
      id: 'project-id:job_D3tTAICe8jSlPuOw8CSvLEKs7-0C',
      selfLink: 'https://www.googleapis.com/bigquery/v2/projects/<project-id>/jobs/job_D3tTAICe8jSlPuOw8CSvLEKs7-0C',
      jobReference:
       { projectId: '<project-id>',
         jobId: 'job_D3tTAICe8jSlPuOw8CSvLEKs7-0C' },

Author: c0b

packages/bigquery/src/index.js

@@ -806,7 +806,7 @@ BigQuery.prototype.getJobs = function(options, callback) {
     }
 
     var jobs = (resp.jobs || []).map(function(jobObject) {
-      var job = that.job(jobObject.id);
+      var job = that.job(jobObject.jobReference.jobId);
       job.metadata = jobObject;
       return job;
     });