[SPARK-16443][SPARKR] Alternating Least Squares (ALS) wrapper

## What changes were proposed in this pull request?

Add Alternating Least Squares wrapper in SparkR. Unit tests have been updated.

## How was this patch tested?

SparkR unit tests.

(If this patch involves UI changes, please attach a screenshot; otherwise, remove this)

![screen shot 2016-07-27 at 3 50 31 pm](https://cloud.githubusercontent.com/assets/15318264/17195347/f7a6352a-5411-11e6-8e21-61a48070192a.png)
![screen shot 2016-07-27 at 3 50 46 pm](https://cloud.githubusercontent.com/assets/15318264/17195348/f7a7d452-5411-11e6-845f-6d292283bc28.png)

Author: Junyang Qian <junyangq@databricks.com>

Closes #14384 from junyangq/SPARK-16443.