SPARK-4022 [CORE] [MLLIB] [WIP] Replace colt dependency (LGPL) with commons-math

This change replaces usages of colt with commons-math3 equivalents, and makes some minor necessary adjustments to related code and tests to match.
Well19937c is the default. We can construct PoissonDistribution with just `mean` and then call `reseedRandomGenerator`:

http://commons.apache.org/proper/commons-math/apidocs/org/apache/commons/math3/distribution/AbstractRealDistribution.html#reseedRandomGenerator(long)