`insert-segment-to-db` is a tool that can insert segments into Druid metadata storage. It is intended to be used
to update the segment table in metadata storage after people manually migrate segments from one place to another.
It can also be used to insert missing segment into Druid, or even recover metadata storage by telling it where the
segments are stored.
Note: This tool expects users to have Druid cluster running in a "safe" mode, where there are no active tasks to interfere
the segments being inserted. Users can optionally bring down the cluster to make 100% sure nothing is interfering.
1) Remove maven client from downloading extensions at runtime.
2) Provide a way to load Druid extensions and hadoop dependencies through file system.
3) Refactor pull-deps so that it can download extensions into extension directories.
4) Add documents on how to use this new extension loading mechanism.
5) Change the way how Druid tarball is generated. Now all the extensions + hadoop-client 2.3.0
are packaged within the Druid tarball.