[SPARK-11263][SPARKR] lintr Throws Warnings on Commented Code in Documentation

Clean out hundreds of `style: Commented code should be removed.` from lintr

Like these:
```
/opt/spark-1.6.0-bin-hadoop2.6/R/pkg/R/DataFrame.R:513:3: style: Commented code should be removed.
# sc <- sparkR.init()
  ^~~~~~~~~~~~~~~~~~~
/opt/spark-1.6.0-bin-hadoop2.6/R/pkg/R/DataFrame.R:514:3: style: Commented code should be removed.
# sqlContext <- sparkRSQL.init(sc)
  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/opt/spark-1.6.0-bin-hadoop2.6/R/pkg/R/DataFrame.R:515:3: style: Commented code should be removed.
# path <- "path/to/file.json"
  ^~~~~~~~~~~~~~~~~~~~~~~~~~~
```

tried without export or rdname, neither work
instead, added this `#' noRd` to suppress .Rd file generation

also updated `family` for DataFrame functions for longer descriptive text instead of `dataframe_funcs`
![image](https://cloud.githubusercontent.com/assets/8969467/10933937/17bf5b1e-8291-11e5-9777-40fc632105dc.png)

this covers *most* of 'Commented code' but I left out a few that looks legitimate.

Author: felixcheung <felixcheung_m@hotmail.com>

Closes #9463 from felixcheung/rlintr.