[SPARK-4378][MLLIB] make ALS more Java-friendly

Add Java-friendly version of `run` and `predict`, and use bulk prediction in Java unit tests. The user guide update will come later (though we may not save many lines of code there). srowen

Author: Xiangrui Meng <meng@databricks.com>

Closes #3240 from mengxr/SPARK-4378 and squashes the following commits:

6581503 [Xiangrui Meng] check number of predictions
6c8bbd1 [Xiangrui Meng] make ALS more Java-friendly
[HOT FIX] make-distribution.sh fails if Yarn shuffle jar DNE

This is introduced in #3147 and is failing builds without the `-Pyarn` profile.

Author: Andrew Or <andrew@databricks.com>

Closes #3250 from andrewor14/fix-yarn-shuffle-build and squashes the following commits:

42b3d37 [Andrew Or] Do not fail fast if Yarn shuffle jar does not exist