Remove unmanaged dependencies(asynchbase) and speficy it on build.sbt

Currently there is asynchbase jar in s2core/lib folder. for source release, I think we can't include any binary in our source release package, so I am suggesting remove jar file in project.

Alternately we can specify as following on our build.sbt.

"org.hbase" % "asynchbase" % "1.7.2-S2GRAPH" from "https://github.com/SteamShon/asynchbase/raw/mvn-repo/org/hbase/asynchbase/1.7.2-S2GRAPH/asynchbase-1.7.2-S2GRAPH-jar-with-dependencies.jar"