added simple model of user_timeline jobs and errors for recordkeeping, closes #65
Merge branch 'master' into t65-daily-timeline-report
Added TwitterUserTimeLineErrors for case where twitter user has no uid; and for error getting api connection.  Renamed migration script from 0022 to 0023 to avoid conflict with 0022 script recently merged in as part of pull request #123.
Added back print skipmsg (when skipping a user).  Inadvertently removed it on the previous commit.
Merge pull request #124 from gwu-libraries/t65-daily-timeline-report

added simple model of user_timeline jobs and errors for recordkeeping, c...