upgrade to latest libraries

[barrybecker4]

Things to upgrade:
java 8 -> 11 ( I was able to set this in the IDE, but it's really not part of the build)
scala 2.12 -> 2.13.x
When I try I get "bad option: '-Ywarn-inaccessible". Also nd4j may not support it yet.
nd4j 1.0.0-beta3 -> 1.0.0-beta6
I found that 1.0.6 has memory leak issues, especially when used with CUDA and GPU.
etc

[barrybecker4]

Note: ND4J is not yet compatible with scala 2.13.1 as of 1.0.0-beta6

[barrybecker4]

I updated scalatest and use 1.0.0-beta3 of nd4j.

[barrybecker4]

Travis CI build now uses opensdk11.