Reduce number of maven dependencies for dg-core

[sujitrect]

I am a new user and thought that this small utility should have very less dependencies but was amazed to find that the maven dependency jars it(dg-core) has/downloads is a huge 135 jars. Naturally the initial setup took a very long time for me (as my mvn repo didnt have all these jars). Moreover, this is a bottleneck if i want to embed this in some high level project. Can you please evaluate to keep the bare minimum dependencies?

[mibrahim]

Agreed. We're looking into it.

[dovidkopel]

We will take out the Spark related dependencies and the classes that utilize them and make that into a sub-module off of dg-core.