 Only rebuild needed modules between different scala version builds (#1784)
 Only rebuild needed modules between different scala version builds (#1784)

Reduces build time of `./buildmultiplescalaversions.sh clean install -DskipTests=t
   from 184s to 107s

Fixes https://github.com/deeplearning4j/deeplearning4j/issues/2873
ambraspace/nd4j,deeplearning4j/nd4j,gagatust/nd4j,deeplearning4j/nd4j,smarthi/nd4j,smarthi/nd4j,ambraspace/nd4j,gagatust/nd4j,huitseeker/nd4j,huitseeker/nd4j