Update RealtimePlumberSchool.java

There was an issue if you restart realtime node and merged dir is still there it will throw exceptions. To tackle this issue a check has been added. So now only persisted dir/files will be read and anything from "merged" will be avoided.
Update RealtimePlumberSchool.java

Put a check to make sure that we're only looking for the folder those have number-only names, to avoid "merged" directory issue.
Upgraded to twitter4j 3.0.3, twitter example now works with twitter4j.properties in place that lists key pairs.
Fixed interactive twitter example to ask for consumer/access keys and secrets upon run.
Merge pull request #166 from rjurney/master

Fixed auth problem with twitter example
Merge pull request #158 from kOD-dKOD/master

Tackle "merged" dir. issue after restarting realtime node
1) Fix truncation math when figuring out what Segments to persist for realtime plumber.  Previously, Sinks could get persist-n-merged without actually being ready to be persist-n-merged. Fixes #168
Merge branch 'master' of github.com:metamx/druid
Merge branch 'master' into batch-zk