[SPARK-10106] [SPARKR] Add `ifelse` Column function to SparkR

### JIRA
[[SPARK-10106] Add `ifelse` Column function to SparkR - ASF JIRA](https://issues.apache.org/jira/browse/SPARK-10106)

Author: Yu ISHIKAWA <yuu.ishikawa@gmail.com>

Closes #8303 from yu-iskw/SPARK-10106.